Secondary battery, battery pack, electric vehicle, electric power storage system, electric power tool, and electronic apparatus

ABSTRACT

A secondary battery includes: a cathode; an anode; and an electrolytic solution. The anode includes an anode active material layer on an anode current collector. The anode active material layer includes a carbon material. The anode active material layer has a thickness from about 30 micrometers to about 100 micrometers both inclusive. The electrolytic solution includes an unsaturated cyclic ester carbonate represented by the following Formula (1). 
     
       
         
         
             
             
         
       
     
     (X is a divalent group in which m-number of &gt;C═CR1R2 and n-number of &gt;CR3R4 are bonded in any order. Each of R1 to R4 is one of a hydrogen group, a halogen group, a monovalent hydrocarbon group, a monovalent halogenated hydrocarbon group, a monovalent oxygen-containing hydrocarbon group, and a monovalent halogenated oxygen-containing hydrocarbon group. Any two or more of the R1 to the R4 are allowed to be bonded to one another. m and n satisfy m≧1 and n≧0.)

CROSS REFERENCES TO RELATED APPLICATIONS

The present application claims priority to Japanese Priority PatentApplication JP 2012-041562 filed in the Japan Patent Office on Feb. 28,2012, the entire content of which is hereby incorporated by reference.

BACKGROUND

The present application relates to a secondary battery including acathode, an anode, and an electrolytic solution, and to a battery pack,an electric vehicle, an electric power storage system, an electric powertool, and an electronic apparatus that use the secondary battery.

In recent years, various electronic apparatuses such as a mobile phoneand a personal digital assistant (PDA) have been widely used, and it hasbeen demanded to further reduce the size and the weight of theelectronic apparatuses and to achieve their long life. Accordingly, asan electric power source for the electronic apparatuses, a battery, inparticular, a small and light-weight secondary battery capable ofproviding high energy density has been developed. In these days, it hasbeen considered to apply such a secondary battery to various otherapplications in addition to the foregoing electronic apparatuses.Representative examples of such other applications include a batterypack attachably and detachably mounted on the electronic apparatuses orthe like, an electric vehicle such as an electric automobile, anelectric power storage system such as a home electric power server, andan electric power tool such as an electric drill.

As the secondary battery, secondary batteries that obtain a batterycapacity by utilizing various charge and discharge principles have beenproposed. In particular, a secondary battery utilizing insertion andextraction of an electrode reactant is considered promising, since sucha secondary battery provides higher energy density than lead batteries,nickel-cadmium batteries, and the like.

The secondary battery includes a cathode, an anode, and an electrolyticsolution. The electrolytic solution contains a solvent and anelectrolyte salt. The electrolytic solution functioning as a medium fora charge and discharge reaction largely affects performance of thesecondary battery. Therefore, various studies have been made on thecomposition of the electrolytic solution. Specifically, to suppressbattery degradation at the time of high-voltage charging, explosionhazard due to pressure increase inside a battery, and/or the like, acyclic ester carbonate having one or more carbon-carbon unsaturatedbonds is used as an additive of an electrolytic solution (for example,see Japanese Unexamined Patent Application Publication Nos. 2006-114388,2001-135351, H11-191319, 2000-058122, and 2008-010414, and JapaneseUnexamined Patent Application Publication (Translation of PCTApplication) No. 2004-523073). This kind of cyclic ester carbonate isused not only for a battery (liquid battery) using an electrolyticsolution, but also for a battery not using an electrolytic solution(solid state battery) (for example, see Japanese Unexamined PatentApplication Publication No. 2003-017121).

SUMMARY

In recent years, high performance and multi-functions of the electronicapparatuses and the like to which the secondary battery is applied areincreasingly developed. Therefore, further improvement of the batterycharacteristics has been desired.

It is desirable to provide a secondary battery capable of providingsuperior battery characteristics, a battery pack, an electric vehicle,an electric power storage system, an electric power tool, and anelectronic apparatus.

According to an embodiment of the present application, there is provideda secondary battery including: a cathode; an anode; and an electrolyticsolution. The anode includes an anode active material layer on an anodecurrent collector. The anode active material layer includes a carbonmaterial. The anode active material layer has a thickness from about 30micrometers to about 100 micrometers both inclusive. The electrolyticsolution includes an unsaturated cyclic ester carbonate represented bythe following Formula (1).

(X is a divalent group in which m-number of >C═CR1R2 and n-numberof >CR3R4 are bonded in any order. Each of R1 to R4 is one of a hydrogengroup, a halogen group, a monovalent hydrocarbon group, a monovalenthalogenated hydrocarbon group, a monovalent oxygen-containinghydrocarbon group, and a monovalent halogenated oxygen-containinghydrocarbon group. Any two or more of the R1 to the R4 are allowed to bebonded to one another. m and n satisfy m≧1 and n≧0.)

According to an embodiment of the present application, there is provideda battery pack including: a secondary battery; a control sectioncontrolling a used state of the secondary battery; and a switch sectionswitching the used state of the secondary battery according to aninstruction of the control section. The secondary battery includes acathode, an anode, and an electrolytic solution. The anode includes ananode active material layer on an anode current collector. The anodeactive material layer includes a carbon material. The anode activematerial layer has a thickness from about 30 micrometers to about 100micrometers both inclusive. The electrolytic solution includes anunsaturated cyclic ester carbonate represented by the following Formula(1).

(X is a divalent group in which m-number of >C═CR1R2 and n-numberof >CR3R4 are bonded in any order. Each of R1 to R4 is one of a hydrogengroup, a halogen group, a monovalent hydrocarbon group, a monovalenthalogenated hydrocarbon group, a monovalent oxygen-containinghydrocarbon group, and a monovalent halogenated oxygen-containinghydrocarbon group. Any two or more of the R1 to the R4 are allowed to bebonded to one another. m and n satisfy m≧1 and n≧0.)

According to an embodiment of the present application, there is providedan electric vehicle including: a secondary battery; a conversion sectionconverting electric power supplied from the secondary battery into drivepower; a drive section operating according to the drive power; and acontrol section controlling a used state of the secondary battery. Thesecondary battery includes a cathode, an anode, and an electrolyticsolution. The anode includes an anode active material layer on an anodecurrent collector. The anode active material layer includes a carbonmaterial. The anode active material layer has a thickness from about 30micrometers to about 100 micrometers both inclusive. The electrolyticsolution includes an unsaturated cyclic ester carbonate represented bythe following Formula (1).

(X is a divalent group in which m-number of >C═CR1R2 and n-numberof >CR3R4 are bonded in any order. Each of R1 to R4 is one of a hydrogengroup, a halogen group, a monovalent hydrocarbon group, a monovalenthalogenated hydrocarbon group, a monovalent oxygen-containinghydrocarbon group, and a monovalent halogenated oxygen-containinghydrocarbon group. Any two or more of the R1 to the R4 are allowed to bebonded to one another. m and n satisfy m≧1 and n≧0.)

According to an embodiment of the present application, there is providedan electric power storage system including: a secondary battery; one ormore electric devices supplied with electric power from the secondarybattery; and a control section controlling the supplying of the electricpower from the secondary battery to the one or more electric devices.The secondary battery includes a cathode, an anode, and an electrolyticsolution. The anode includes an anode active material layer on an anodecurrent collector. The anode active material layer includes a carbonmaterial. The anode active material layer has a thickness from about 30micrometers to about 100 micrometers both inclusive. The electrolyticsolution includes an unsaturated cyclic ester carbonate represented bythe following Formula (1).

(X is a divalent group in which m-number of >C═CR1R2 and n-numberof >CR3R4 are bonded in any order. Each of R1 to R4 is one of a hydrogengroup, a halogen group, a monovalent hydrocarbon group, a monovalenthalogenated hydrocarbon group, a monovalent oxygen-containinghydrocarbon group, and a monovalent halogenated oxygen-containinghydrocarbon group. Any two or more of the R1 to the R4 are allowed to bebonded to one another. m and n satisfy m≧1 and n≧0.)

According to an embodiment of the present application, there is providedan electric power tool including: a secondary battery; and a movablesection being supplied with electric power from the secondary battery.The secondary battery includes a cathode, an anode, and an electrolyticsolution. The anode includes an anode active material layer on an anodecurrent collector. The anode active material layer includes a carbonmaterial. The anode active material layer has a thickness from about 30micrometers to about 100 micrometers both inclusive. The electrolyticsolution includes an unsaturated cyclic ester carbonate represented bythe following Formula (1).

(X is a divalent group in which m-number of >C═CR1R2 and n-numberof >CR3R4 are bonded in any order. Each of R1 to R4 is one of a hydrogengroup, a halogen group, a monovalent hydrocarbon group, a monovalenthalogenated hydrocarbon group, a monovalent oxygen-containinghydrocarbon group, and a monovalent halogenated oxygen-containinghydrocarbon group. Any two or more of the R1 to the R4 are allowed to bebonded to one another. m and n satisfy m≧1 and n≧0.)

According to an embodiment of the present application, there is providedan electronic apparatus comprising a secondary battery as an electricpower supply source. The secondary battery includes a cathode, an anode,and an electrolytic solution. The anode includes an anode activematerial layer on an anode current collector. The anode active materiallayer includes a carbon material. The anode active material layer has athickness from about 30 micrometers to about 100 micrometers bothinclusive. The electrolytic solution includes an unsaturated cyclicester carbonate represented by the following Formula (1).

(X is a divalent group in which m-number of >C═CR1R2 and n-numberof >CR3R4 are bonded in any order. Each of R1 to R4 is one of a hydrogengroup, a halogen group, a monovalent hydrocarbon group, a monovalenthalogenated hydrocarbon group, a monovalent oxygen-containinghydrocarbon group, and a monovalent halogenated oxygen-containinghydrocarbon group. Any two or more of the R1 to the R4 are allowed to bebonded to one another. m and n satisfy m≧1 and n≧0.)

The foregoing thickness of the anode active material layer refers to athickness of one anode active material layer, that is, a thickness ofthe anode active material layer on one side of the anode currentcollector. Therefore, in the case where the anode active material layeris provided only on one side of the anode current collector, theforegoing thickness of the anode active material layer refers to thethickness of that anode active material layer on one side of the anodecurrent collector. On the other hand, in the case where the anode activematerial layers are provided on both sides of the anode currentcollector, the foregoing thickness of the anode active material layerrefers to a thickness of each anode active material layer.

According to the secondary battery according to the embodiment of thepresent application, since the anode active material layer contains acarbon material, the thickness of the anode active material layer isfrom about 30 μm to about 100 μm both inclusive, and the electrolyticsolution contains the unsaturated cyclic ester carbonate, superiorbattery characteristics are obtainable. Further, according to thebattery pack, the electric vehicle, the electric power storage system,the electric power tool, and the electronic apparatus according to theembodiments of the present application, similar effects are obtainable.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary, and are intended toprovide further explanation of the application as claimed.

Additional features and advantages are described herein, and will beapparent from the following Detailed Description and the figures.

BRIEF DESCRIPTION OF THE FIGURES

The accompanying drawings are included to provide a furtherunderstanding of the disclosure, and are incorporated in and constitutea part of this specification. The drawings illustrate embodiments and,together with the specification, serve to explain the principles of theapplication.

FIG. 1 is a cross-sectional view illustrating a configuration of asecondary battery (cylindrical type) according to an embodiment of thepresent application.

FIG. 2 is a cross-sectional view illustrating an enlarged part of aspirally wound electrode body illustrated in FIG. 1.

FIG. 3 is a perspective view illustrating a configuration of anothersecondary battery (laminated film type) according to the embodiment ofthe present application.

FIG. 4 is a cross-sectional view taken along a line IV-IV of a spirallywound electrode body illustrated in FIG. 3.

FIG. 5 is a block diagram illustrating a configuration of an applicationexample (battery pack) of the secondary battery.

FIG. 6 is a block diagram illustrating a configuration of an applicationexample (electric vehicle) of the secondary battery.

FIG. 7 is a block diagram illustrating a configuration of an applicationexample (electric power storage system) of the secondary battery.

FIG. 8 is a block diagram illustrating a configuration of an applicationexample (electric power tool) of the secondary battery.

DETAILED DESCRIPTION

An embodiment of the present application will be hereinafter describedin detail with reference to the drawings. The description will be givenin the following order.

1. Secondary Battery

1-1. Cylindrical Type

1-2. Laminated Film Type

2. Applications of Secondary Battery 2-1. Battery Pack

2-2. Electric Vehicle

2-3. Electric Power Storage System

2-4. Electric Power Tool

[1. Secondary Battery]

[1-1. Cylindrical Type]

FIG. 1 and FIG. 2 illustrate cross-sectional configurations of asecondary battery according to an embodiment of the present application.FIG. 2 illustrates enlarged part of a spirally wound electrode body 20illustrated in FIG. 1.

[Whole Configuration of Secondary Battery]

The secondary battery herein described is a lithium ion secondarybattery in which the capacity of an anode 22 is obtained by insertionand extraction of Li (lithium ions) as an electrode reactant.

The secondary battery is what we call a cylindrical-type secondarybattery. The secondary battery contains the spirally wound electrodebody 20 and a pair of insulating plates 12 and 13 inside a battery can11 in the shape of a substantially hollow cylinder. In the spirallywound electrode body 20, for example, a cathode 21 and the anode 22 arelayered with a separator 23 in between and are spirally wound.

The battery can 11 has a hollow structure in which one end of thebattery can 11 is closed and the other end of the battery can 11 isopened. The battery can 11 may be made of, for example, iron, aluminum,an alloy thereof, or the like. It is to be noted that the surface of thebattery can 11 may be plated with nickel or the like. The pair ofinsulating plates 12 and 13 is arranged to sandwich the spirally woundelectrode body 20 in between, and to extend perpendicularly to thespirally wound periphery surface.

At the open end of the battery can 11, a battery cover 14, a safetyvalve mechanism 15, and a positive temperature coefficient device (PTCdevice) 16 are attached by being swaged with a gasket 17. Thereby, thebattery can 11 is hermetically sealed. The battery cover 14 may be madeof, for example, a material similar to that of the battery can 11. Thesafety valve mechanism 15 and the PTC device 16 are provided inside thebattery cover 14. The safety valve mechanism 15 is electricallyconnected to the battery cover 14 through the PTC device 16. In thesafety valve mechanism 15, in the case where the internal pressurebecomes a certain level or more by internal short circuit, externalheating, or the like, a disk plate 15A inverts to cut electricconnection between the battery cover 14 and the spirally wound electrodebody 20. The PTC device 16 prevents abnormal heat generation resultingfrom a large current. As temperature rises, resistance of the PTC device16 is increased accordingly. The gasket 17 may be made of, for example,an insulating material. The surface of the gasket 17 may be coated withasphalt.

In the center of the spirally wound electrode body 20, for example, acenter pin 24 is inserted. However, the center pin 24 is not necessarilyincluded therein. For example, a cathode lead 25 made of a conductivematerial such as aluminum is connected to the cathode 21. For example,an anode lead 26 made of a conductive material such as nickel isconnected to the anode 22. The cathode lead 25 is attached to the safetyvalve mechanism 15 by welding or the like, and is electrically connectedto the battery cover 14. The anode lead 26 is attached to the batterycan 11 by welding or the like, and is electrically connected to thebattery can 11.

[Cathode]

The cathode 21 has a cathode active material layer 21B on a singlesurface or both surfaces of a cathode current collector 21A. The cathodecurrent collector 21A may be made of, for example, a conductive materialsuch as aluminum, nickel, and stainless steel.

The cathode active material layer 21B contains, as cathode activematerials, one or more of cathode materials capable of inserting andextracting lithium ions. The cathode active material layer 21B mayfurther contain other materials such as a cathode binder and a cathodeelectric conductor as necessary.

The cathode material is preferably a lithium-containing compound, sincehigh energy density is obtained thereby. Examples of thelithium-containing compound include a lithium-transition-metal compositeoxide and a lithium-transition-metal-phosphate compound. Thelithium-transition-metal composite oxide is an oxide containing Li andone or more transition metal elements as constituent elements. Thelithium-transition-metal-phosphate compound is a phosphate compoundcontaining Li and one or more transition metal elements as constituentelements. In particular, it is preferable that the transition metalelement be one or more of Co, Ni, Mn, Fe, and the like, since a highervoltage is obtained thereby. The chemical formula thereof is expressedby, for example, Li_(x)M1O₂ or Li_(y)M2PO₄. In the formulas, M1 and M2represent one or more transition metal elements. Values of x and y varyaccording to the charge and discharge state, and are generally in therange of 0.05≦x≦1.10 and 0.05≦y≦1.10.

Examples of the lithium-transition-metal composite oxide include LiCoO₂,LiNiO₂, and a lithium-nickel-based composite oxide represented by thefollowing Formula (20). Examples of thelithium-transition-metal-phosphate compound include LiFePO₄ andLiFe_(1-u)Mn_(u)PO₄ (u<1), since thereby, a high battery capacity isobtained and superior cycle characteristics are obtained.

LiNi_(1-z)M_(z)O₂  (20)

In Formula (20), M is one or more of Co, Mn, Fe, Al, V, Sn, Mg, Ti, Sr,Ca, Zr, Mo, Tc, Ru, Ta, W, Re, Yb, Cu, Zn, Ba, B, Cr, Si, Ga, P, Sb, andNb. z satisfies 0.005<z<0.5.

In addition thereto, the cathode material may be, for example, an oxide,a disulfide, a chalcogenide, a conductive polymer, or the like. Examplesof the oxide include titanium oxide, vanadium oxide, and manganesedioxide. Examples of the disulfide include titanium disulfide andmolybdenum sulfide. Examples of the chalcogenide include niobiumselenide. Examples of the conductive polymer include sulfur,polyaniline, and polythiophene. However, the cathode material is notlimited to the foregoing materials.

Examples of the cathode binder include one or more of synthetic rubbers,polymer materials, and the like. Examples of the synthetic rubberinclude a styrene-butadiene-based rubber, a fluorine-based rubber, andethylene propylene diene. Examples of the polymer material includepolyvinylidene fluoride and polyimide.

Examples of the cathode electric conductor include one or more of carbonmaterials and the like. Examples of the carbon materials includegraphite, carbon black, acetylene black, and Ketjen black. The cathodeelectric conductor may be a metal material, a conductive polymer, or thelike as long as the material has electric conductivity.

[Anode]

The anode 22 has an anode active material layer 22B on a single surfaceor both surfaces of an anode current collector 22A.

The anode current collector 22A may be made of, for example, aconductive material such as copper, nickel, and stainless steel. Thesurface of the anode current collector 22A is preferably roughened.Thereby, due to what we call an anchor effect, adhesion characteristicsof the anode active material layer 22B with respect to the anode currentcollector 22A are improved. In this case, it is enough that the surfaceof the anode current collector 22A in a region opposed to the anodeactive material layer 22B is roughened at minimum. Examples ofroughening methods include a method of forming fine particles byelectrolytic treatment. The electrolytic treatment is a method ofproviding concavity and convexity by forming fine particles on thesurface of the anode current collector 22A by an electrolytic method inan electrolytic bath. A copper foil fabricated by an electrolytic methodis generally called “electrolytic copper foil”.

The anode active material layer 22B contains one or more of anodematerials capable of inserting and extracting lithium ions as anodeactive materials, and may also contain other materials such as an anodebinder and an anode electric conductor as necessary. Details of theanode binder and the anode electric conductor are, for example, similarto those of the cathode binder and the cathode electric conductor,respectively. However, the chargeable capacity of the anode material ispreferably larger than the discharge capacity of the cathode 21 in orderto prevent lithium metal from being unintentionally precipitated on theanode 22 in the middle of charge.

The anode material is a carbon material. In the carbon material, itscrystal structure change at the time of insertion and extraction oflithium ions is extremely small. Therefore, the carbon material provideshigh energy density and superior cycle characteristics. Further, thecarbon material functions as an anode electric conductor as well.Examples of the carbon material include graphitizable carbon,non-graphitizable carbon in which the spacing of (002) plane is equal toor greater than 0.37 nm, and graphite in which the spacing of (002)plane is equal to or smaller than 0.34 nm. More specifically, examplesof the carbon material include pyrolytic carbons, cokes, glassy carbonfiber, an organic polymer compound fired body, activated carbon, andcarbon blacks. Of the foregoing, examples of the cokes include pitchcoke, needle coke, and petroleum coke. The organic polymer compoundfired body is obtained by firing (carbonizing) a polymer compound suchas a phenol resin and a furan resin at appropriate temperature. Inaddition thereto, the carbon material may be low crystalline carbon oramorphous carbon heat-treated at temperature of about 1000 deg C. orless. It is to be noted that the shape of the carbon material may be anyof a fibrous shape, a spherical shape, a granular shape, and ascale-like shape.

It is to be noted that the anode active material layer 22B may furthercontain other types of anode material as long as such an anode materialcontains a carbon material as an anode active material. Examples of suchother type of anode material include a material containing one or moreof metal elements and metalloid elements capable of forming an alloywith Li as constituent elements. Examples of the metal elements andmetalloid elements include Mg, B, Al, Ga, In, Si, Ge, Sn, Pb, Bi, Cd,Ag, Zn, Hf, Zr, Y, Pd, and Pt. In particular, Si, Sn, or both arepreferable. Si and Sn have a superior ability of inserting andextracting lithium ions, and therefore, provide high energy density.Further, other anode material may be, for example, a metal oxide, apolymer compound, or the like. Examples of the metal oxide include ironoxide, ruthenium oxide, and molybdenum oxide. Examples of the polymercompound include polyacetylene, polyaniline, and polypyrrole.

The anode active material layer 22B is formed by, for example, a coatingmethod, a firing method (sintering method), or a combination of two ormore of these methods. The coating method is a method in which, forexample, after a particulate (powder) anode active material is mixedwith an anode binder and/or the like, the mixture is dispersed in asolvent such as an organic solvent, and the anode current collector iscoated with the resultant. As the firing method, a publicly-knowntechnique may be used. Examples of the firing method include anatmosphere firing method, a reactive firing method, and a hot pressfiring method.

In the secondary battery, as described above, in order to preventlithium metal from being unintentionally precipitated on the anode 22 inthe middle of charge, the electrochemical equivalent of the anodematerial capable of inserting and extracting lithium ions is preferablylarger than the electrochemical equivalent of the cathode. Further, inthe case where the open circuit voltage (that is, a battery voltage) incompletely-charged state is equal to or greater than 4.25 V, theextraction amount of lithium ions per unit mass is larger than that inthe case where the open circuit voltage is 4.2 V even if the samecathode active material is used. Therefore, amounts of the cathodeactive material and the anode active material are adjusted accordingly.Thereby, high energy density is obtainable.

The thickness of the anode active material layer 22B is equal to orlarger than 30 μm, and more specifically, is from 30 μm to 100 μm bothinclusive. In the case where the thickness of the anode active materiallayer 22B is in the foregoing range, and the electrolytic solutioncontains an after-mentioned unsaturated cyclic ester carbonate, thechemical stability of the electrolytic solution is significantlyimproved compared to in the case where the thickness of the anode activematerial layer 22B is out of the foregoing range. Thereby, even if thesecondary battery is repeatedly charged and discharged, or the secondarybattery is stored at high temperature, a decomposition reaction of theelectrolytic solution is suppressed.

The foregoing thickness of the anode active material layer 22B refers tothe thickness of one anode active material layer 22B, that is, thethickness of the anode active material layer 22B on one side of theanode current collector 22A. Therefore, in the case where the anodeactive material layer 22B is provided only on one side of the anodecurrent collector 22A, the foregoing thickness of the anode activematerial layer 22B refers to the thickness of that anode active materiallayer 22B on one side of the anode current collector 22A. On the otherhand, in the case where the anode active material layers 22B arerespectively provided on both sides of the anode current collector 22A,the foregoing thickness of the anode active material layer 22B refers tothe thickness of each anode active material layer 22B.

Although the volume density of the anode active material layer 22B isnot particularly limited, in particular, the volume density thereof ispreferably from 1.4 g/cm³ to 1.95 g/cm³ both inclusive. In this case,the volume density thereof is more preferably from 1.6 g/cm³ to 1.95g/cm³ both inclusive, and much more preferably from 1.6 g/cm³ to 1.85g/cm³ both inclusive. One reason for this is that, in these cases, whileenergy density and/or the like is secured, the chemical stability of theelectrolytic solution is further improved. More specifically, in thecase where the volume density of the anode active material layer 22B issmaller than 1.4 g/cm³, there is a possibility that sufficient energydensity is not obtained. On the other hand, in the case where the volumedensity of the anode active material layer 22B is larger than 1.95g/cm³, efficiency of inserting and extracting lithium ions may belowered, and impregnation characteristics of the electrolytic solutionwith respect to the anode active material layer 22B may be lowered.

In the case where the anode active material layer 22B contains othermaterials such as an anode binder together with the anode activematerial, the mixture ratio between the anode active material and othermaterials is not particularly limited. Specifically, the mixture ratio(weight ratio) between the anode active material and other materials ispreferably from 99:1 to 85:15. Thereby, while energy density and/or thelike is secured, the chemical stability of the electrolytic solution isfurther improved. More specifically, in the case where the ratio of theanode active material is excessively small, there is a possibility thatsufficient energy density is not obtainable. On the other hand, in thecase where the ratio of the anode active material is excessively large,adhesive characteristics and the like may be lowered.

[Separator]

The separator 23 separates the cathode 21 from the anode 22, and passeslithium ions while preventing current short circuit resulting fromcontact of both electrodes. The separator 23 is, for example, a porousfilm made of a synthetic resin, ceramics, or the like. The separator 23may be a laminated film in which two or more types of porous films arelaminated. Examples of the synthetic resin includepolytetrafluoroethylene, polypropylene, and polyethylene.

In particular, the separator 23 may include, for example, the foregoingporous film (base material layer) and a polymer compound layer providedon one surface or both surfaces of the base material layer. Thereby,adhesion characteristics of the separator 23 with respect to the cathode21 and the anode 22 are improved, and therefore, skewness of thespirally wound electrode body 20 is suppressed. Thereby, a decompositionreaction of the electrolytic solution is suppressed, and liquid leakageof the electrolytic solution with which the base material layer isimpregnated is suppressed. Accordingly, even if charge and discharge arerepeated, the resistance of the secondary battery is less likely to beincreased, and battery swollenness is suppressed.

The polymer compound layer contains, for example, a polymer materialsuch as polyvinylidene fluoride, since such a polymer material has asuperior physical strength and is electrochemically stable. However, thepolymer material may be a material other than polyvinylidene fluoride.The polymer compound layer is formed as follows, for example. That is,after a solution in which the polymer material is dissolved is prepared,the base material layer is coated with the solution, and the resultantis subsequently dried. Alternatively, the base material layer may besoaked in the solution and may be subsequently dried.

[Electrolytic Solution]

The separator 23 is impregnated with an electrolytic solution as aliquid electrolyte. The electrolytic solution contains one or more ofunsaturated cyclic ester carbonates represented by the following Formula(1) (hereinafter, simply referred to as “unsaturated cyclic estercarbonate”). However, the electrolytic solution may contain othermaterial such as a solvent and an electrolyte salt.

In Formula (1), X is a divalent group in which m-number of >C═CR1R2 andn-number of >CR3R4 are bonded in any order. Each of R1 to R4 is one of ahydrogen group, a halogen group, a monovalent hydrocarbon group, amonovalent halogenated hydrocarbon group, a monovalent oxygen-containinghydrocarbon group, and a monovalent halogenated oxygen-containinghydrocarbon group. Any two or more of R1 to R4 may be bonded to eachother. m and n satisfy m≧1 and n≧0.

The unsaturated cyclic ester carbonate refers to a cyclic estercarbonate having one or more unsaturated bonds (>C═C< as carbon-carbondouble bonds). One reason why the electrolytic solution contains theunsaturated cyclic ester carbonate is that, as described above, in thecase where the thickness of the anode active material layer 22B is equalto or larger than 30 μm, and the electrolytic solution contains theunsaturated cyclic ester carbonate, the chemical stability of theelectrolytic solution is significantly improved.

More specifically, in the case where the thickness of the anode activematerial layer 22B is less than 30 μm, even if the electrolytic solutioncontains the unsaturated cyclic ester carbonate, the chemical stabilityof the electrolytic solution is not improved. One reason for this may bethat, since at the time of charge, an expansion amount per unit area ofthe anode 22 is small and an amount of reaction between the anode 22 andthe electrolytic solution is small, a function of suppressingdecomposition of the electrolytic solution by the unsaturated cyclicester carbonate is not substantially exercised. On the other hand, inthe case where the thickness of the anode active material layer 22B isequal to or larger than 30 μm, and the electrolytic solution containsthe unsaturated cyclic ester carbonate, the chemical stability of theelectrolytic solution is improved. One reason for this may be that,since, at the time of charge, an expansion amount per unit area of theanode 22 is large and an amount of reaction between the anode 22 and theelectrolytic solution is large, a function of suppressing decompositionof the electrolytic solution by the unsaturated cyclic ester carbonateis substantially exercised. Such a tendency that the chemical stabilityof the electrolytic solution is improved is significant under strictconditions such as a high-temperature environment.

X in Formula (1) is a group obtained by bonding m-number of >C═CR1R2 ton-number of >CR3R4 so that the valency becomes divalent as a whole (onebonding hand exists on each of both ends). Adjacent groups (groupsbonded to each other) may be the same type of group such as >C═CR1R2and >C═CR1R2, or may be different from each other such as >C═CR1-R2and >CR3R4. That is, the number (m) of >C═CR1R2 used for forming thedivalent group and the number (n) of >CR3R4 used for forming thedivalent group may be any number, and the bonding order thereof may alsobe any order.

While >C═CR1R2 is a divalent unsaturated group having the foregoingcarbon-carbon double bond, >CR3R4 is a divalent saturated group nothaving a carbon-carbon double bond. Since n satisfies n≧0, >CR3R4 as asaturated group is not necessarily included in X. On the other hand,since m satisfies m>1, it may be necessary to include one ormore >C═CR1R2 as an unsaturated group in X typically. Therefore, X maybe configured of only >C═CR1R2, or may be configured of both >C═CR1R2and >CR3R4. One reason for this is that it may be necessary to includeone or more unsaturated groups in a chemical structure of theunsaturated cyclic ester carbonate.

Values of m and n are not particularly limited as long as the conditionsof m≧1 and n≧0 are satisfied. In particular, in the case where >C═CR1R2is >C═CH₂ and >CR3R4 is >CH₂, (m+n)≦5 is preferably satisfied. Onereason for this is that, in this case, the carbon number of X is notexcessively large, and therefore, the solubility and the compatibilityof the unsaturated cyclic ester carbonate are secured.

It is to be noted that any two or more of R1 to R4 in >C═CR1R2and >CR3R4 may be bonded to one another, and the bonded groups may forma ring. As an example, R1 may be bonded to R2, R3 may be bonded to R4,and R2 may be bonded to R3 or R4.

Details of R1 to R4 are described below. R1 to R4 may be the same typeof group, or may be groups different from one another. Any two or threeof R1 to R4 may be the same type of group.

Each type of R1 to R4 is not particularly limited as long as each of R1to R4 is one of a hydrogen group, a halogen group, a monovalenthydrocarbon group, a monovalent halogenated hydrocarbon group, amonovalent oxygen-containing hydrocarbon group, and a monovalenthalogenated oxygen-containing hydrocarbon group. One reason for this isthat, since, in this case, X has one or more carbon-carbon double bonds(>C═CR1R2), the foregoing advantage is obtainable without depending onthe types of R1 to R4.

The halogen group is, for example, one or more of a fluorine group (—F),a chlorine group (—Cl), a bromine group (—Br), an iodine group (—I), andthe like. In particular, the fluorine group is preferable, since ahigher effect is thereby obtainable.

“Monovalent hydrocarbon group” is a generic term used to refer tomonovalent groups configured of C and H, and may have a straight-chainstructure or a branched structure having one or more side chains.Examples of the monovalent hydrocarbon group include an alkyl group withcarbon number from 1 to 12 both inclusive, an alkenyl group with carbonnumber from 2 to 12 both inclusive, an alkynyl group with carbon numberfrom 2 to 12 both inclusive, an aryl group with carbon number from 6 to18 both inclusive, and a cycloalkyl group with carbon number from 3 to18 both inclusive. One reason for this is that the foregoing advantageis thereby obtained while the solubility, the compatibility, and thelike of the unsaturated cyclic ester carbonate are secured.

More specific examples of the alkyl group include a methyl group (—CH₃),an ethyl group (—C₂H₅), and a propyl group (—C₃H₇). Examples of thealkenyl group include a vinyl group (—CH═CH₂) and an allyl group(—CH₂—CH═CH₂). Examples of the alkynyl group include an ethynyl group(—C≡CH). Examples of the aryl group include a phenyl group and a naphtylgroup. Examples of the cycloalkyl group include a cyclopropyl group, acyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptylgroup, and a cyclooctyl group.

“Monovalent oxygen-containing hydrocarbon group” is a generic term usedto refer to monovalent groups configured of O together with C and H.Examples of the monovalent oxygen-containing hydrocarbon group includean alkoxy group with carbon number from 1 to 12 both inclusive. Onereason for this is that the foregoing advantage is thereby obtainedwhile the solubility, the compatibility, and the like of the unsaturatedcyclic ester carbonate are secured. More specific examples of the alkoxygroup include a methoxy group (—OCH₃) and an ethoxy group (—OC₂H₅).

It is to be noted that a group obtained by bonding two or more of theforegoing alkyl group and the like so that the whole valency becomesmonovalent may be used. Examples thereof include a group obtained bybonding an alkyl group to an aryl group and a group obtained by bondingan alkyl group to a cycloalkyl group. More specific examples of thegroup obtained by bonding an alkyl group to an aryl group include abenzil group.

“Monovalent halogenated hydrocarbon group” is obtained by substituting(halogenating) each of part or all of hydrogen groups (—H) out of theforegoing monovalent hydrocarbon group by a halogen group. Similarly,“monovalent halogenated oxygen-containing hydrocarbon group” is obtainedby substituting each of part or all of hydrogen groups out of theforegoing monovalent oxygen-containing hydrocarbon group by a halogengroup. In either case, types of the halogen group substituting for ahydrogen group are similar to the types of the halogen group describedabove.

Examples of the monovalent halogenated hydrocarbon group include a groupobtained by halogenating the foregoing alkyl group or the like. That is,the monovalent halogenated hydrocarbon group is a group obtained bysubstituting each of part or all of hydrogen groups of the foregoingalkyl group or the like by a halogen group. More specific examples ofthe group obtained by halogenating an alkyl group or the like include atrifluoromethyl group (—CF₃) and a pentafluoroethyl group (—C₂F₅).Further, examples of the monovalent halogenated oxygen-containinghydrocarbon group include a group obtained by substituting each of partor all of hydrogen groups of the foregoing alkoxy group or the like by ahalogen group. More specific examples of the group obtained byhalogenating an alkoxy group or the like include a trifluoromethoxygroup (—OCF₃) and a pentafluoroethoxy group (—OC₂F₅).

It is to be noted that each of R1 to R4 may be a group other than theforegoing groups. Specifically, each of R1 to R4 may be, for example, aderivative of each of the foregoing groups. The derivative is obtainedby introducing one or more substituent groups to each of the foregoinggroups. Substituent group types may be any type.

In particular, the unsaturated cyclic ester carbonate is preferablyrepresented by the following Formula (2) or the following Formula (3).One reason for this is that, in this case, the foregoing advantage isobtained, and such compounds are easily synthesized.

In Formulas (2) and (3), each of R5 to R10 is one of a hydrogen group, ahalogen group, a monovalent hydrocarbon group, a monovalent halogenatedhydrocarbon group, a monovalent oxygen-containing hydrocarbon group, anda monovalent halogenated oxygen-containing hydrocarbon group. R5 and R6may be bonded to each other, and any two or more of R7 to R10 may bebonded to one another.

Focusing attention on a relation between Formula (1) and Formula (2),the unsaturated cyclic ester carbonate represented by Formula (2) has,as X in Formula (1), one unsaturated group (>C═CH₂) correspondingto >C═CR1R2 and one saturated group (>CR5R6) corresponding to >CR3R4. Onthe other hand, focusing attention on a relation between Formula (1) andFormula (3), the unsaturated cyclic ester carbonate represented byFormula (3) has, as X, one unsaturated group (>C═CH₂) correspondingto >C═CR1R2 and two saturated groups (>CR7R8 and >CR9R10) correspondingto >CR3R4. However, the foregoing one unsaturated group and theforegoing two saturated groups are bonded in order of >CR7R8, >CR9R10,and C═CH₂.

Details of R5 and R6 in Formula (2) and R7 to R10 in Formula (3) aresimilar to those of R1 to R4 in Formula (1), and therefore, descriptionsthereof will be omitted.

Specific examples of the unsaturated cyclic ester carbonate includecompounds represented by the following Formula (1-1) to the followingFormula (1-56). Such unsaturated cyclic ester carbonates include ageometric isomer. However, specific examples of the unsaturated cyclicester carbonate are not limited to the compounds listed in Formula (1-1)to Formula (1-56).

In particular, Formula (1-1) and the like corresponding to Formula (2)or Formula (1-32) and the like corresponding to Formula (3) arepreferable, since a higher effect is thereby obtainable.

Although the content of the unsaturated cyclic ester carbonate in theelectrolytic solution is not particularly limited, in particular, thecontent thereof is preferably from 0.01 wt % to 10 wt % both inclusive,and more preferably from 0.5 wt % to 10 wt % both inclusive since ahigher effect is thereby obtainable.

The solvent used for the electrolytic solution contains one or more ofnonaqueous solvents such as an organic solvent (excluding the foregoingunsaturated cyclic ester carbonate).

Examples of the nonaqueous solvents include a cyclic ester carbonate, achain ester carbonate, lactone, a chain carboxylic ester, and nitrile,since thereby, a superior battery capacity, superior cyclecharacteristics, superior conservation characteristics, and the like areobtained. Examples of the cyclic ester carbonate include ethylenecarbonate, propylene carbonate, and butylene carbonate. Examples of thechain ester carbonate include dimethyl carbonate, diethyl carbonate,ethyl methyl carbonate, and methylpropyl carbonate. Examples of thelactone include γ-butyrolactone and γ-valerolactone. Examples of thecarboxylic ester include methyl acetate, ethyl acetate, methylpropionate, ethyl propionate, methyl butyrate, methyl isobutyrate,methyl trimethylacetate, and ethyl trimethylacetate. Examples of thenitrile include acetonitrile, glutaronitrile, adiponitrile,methoxyacetonitrile, and 3-methoxypropionitrile.

In addition thereto, the nonaqueous solvent may be, for example,1,2-dimethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran,tetrahydropyran, 1,3-dioxolane, 4-methyl-1,3-dioxolane, 1,3-dioxane,1,4-dioxane, N,N-dimethylformamide, N-methylpyrrolidinone,N-methyloxazolidinone, N,N′-dimethylimidazolidinone, nitromethane,nitroethane, sulfolane, trimethyl phosphate, and dimethyl sulfoxide.Thereby, a similar advantage is obtained.

In particular, one or more of ethylene carbonate, propylene carbonate,dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate arepreferable, since thereby, a superior battery capacity, superior cyclecharacteristics, superior conservation characteristics, and the like areobtained. In this case, a combination of a high viscosity (highdielectric constant) solvent (for example, specific dielectric constant∈≧30) such as ethylene carbonate and propylene carbonate and a lowviscosity solvent (for example, viscosity≦1 mPa·s) such as dimethylcarbonate, ethylmethyl carbonate, and diethyl carbonate is morepreferable. One reason for this is that the dissociation property of theelectrolyte salt and ion mobility are improved.

In particular, the solvent preferably contains one or more of otherunsaturated cyclic ester carbonates represented by the following Formula(4) and the following Formula (5). One reason for this is that a stableprotective film is formed mainly on the surface of the anode 22 at thetime of charge and discharge, and therefore, a decomposition reaction ofthe electrolytic solution is suppressed. R11 and R12 may be the sametype of group, or may be groups different from each other. Further, R13to R16 may be the same type of group, or may be groups different fromone another. Alternatively, part of R13 to R16 may be the same type ofgroup. The content of other unsaturated cyclic ester carbonate in thesolvent is not particularly limited, and is, for example, from 0.01 wt %to 10 wt % both inclusive. However, specific examples of otherunsaturated cyclic ester carbonate are not limited to theafter-mentioned compounds.

In Formula (4), each of R11 and R12 is one of a hydrogen group and analkyl group.

In Formula (5), each of R13 to R16 is one of a hydrogen group, an alkylgroup, a vinyl group, and an allyl group. One or more of R13 to R16 areeach a vinyl group or an allyl group.

Other unsaturated cyclic ester carbonate represented by Formula (4) is avinylene-carbonate-based compound. Each type of R11 and R12 is notparticularly limited as long as each of R11 and R12 is one of a hydrogengroup and an alkyl group. Examples of the alkyl group include a methylgroup and an ethyl group, and the carbon number of the alkyl group ispreferably from 1 to 12 both inclusive, since superior solubility andsuperior compatibility are thereby obtained. Specific examples of thevinylene-carbonate-based compounds include vinylene carbonate(1,3-dioxole-2-one), methylvinylene carbonate(4-methyl-1,3-dioxole-2-one), ethylvinylene carbonate(4-ethyl-1,3-dioxole-2-one), 4,5-dimethyl-1,3-dioxole-2-one, and4,5-diethyl-1,3-dioxole-2-one. It is to be noted that each of R11 andR12 may be a group obtained by substituting each of part or all ofhydrogen groups of the alkyl group by a halogen group. In this case,specific examples of the vinylene-carbonate-based compounds include4-fluoro-1,3-dioxole-2-one and 4-trifluoromethyl-1,3-dioxole-2-one. Inparticular, vinylene carbonate is preferable, since vinylene carbonateis easily available and provides a high effect.

Other unsaturated cyclic ester carbonate represented by Formula (5) is avinylethylene-carbonate-based compound. Each type of R13 to R16 is notparticularly limited as long as each of R13 to R16 is one of a hydrogengroup, an alkyl group, a vinyl group, and an allyl group, where one ormore of R13 to R16 are each one of a vinyl group and an allyl group. Thetype and the carbon number of the alkyl group are similar to those ofR11 and R12. Specific examples of the vinylethylene-carbonate-basedcompounds include vinylethylene carbonate (4-vinyl-1,3-dioxolane-2-one),4-methyl-4-vinyl-1,3-dioxolane-2-one,4-ethyl-4-vinyl-1,3-dioxolane-2-one,4-n-propyl-4-vinyl-1,3-dioxolane-2-one,5-methyl-4-vinyl-1,3-dioxolane-2-one, 4,4-divinyl-1,3-dioxo lane-2-one,and 4,5-divinyl-1,3-dioxolane-2-one. In particular, vinylethylenecarbonate is preferable, since vinylethylene carbonate is easilyavailable, and provides a high effect. It goes without saying that allof R13 to R16 may be vinyl groups or allyl groups. Alternatively, someof R13 to R16 may be vinyl groups, and the others thereof may be allylgroups.

It is to be noted that other unsaturated cyclic ester carbonate may bethe compounds represented by Formula (4) and Formula (5), or may becatechol carbonate having a benzene ring.

Further, the solvent preferably contains one or more of halogenatedester carbonates represented by the following Formula (6) and thefollowing Formula (7). One reason for this is that a stable protectivefilm is formed mainly on the surface of the anode 22 at the time ofcharge and discharge, and therefore, a decomposition reaction of theelectrolytic solution is suppressed. The halogenated ester carbonaterepresented by Formula (6) is a cyclic ester carbonate having one ormore halogens as constituent elements (halogenated cyclic estercarbonate). The halogenated ester carbonate represented by Formula (7)is a chain ester carbonate having one or more halogens as constituentelements (halogenated chain ester carbonate). R17 to R20 may be the sametype of group, or may be groups different from one another.Alternatively, part of R17 to R20 may be the same type of group. Thesame is applied to R21 to R26. Although the content of the halogenatedester carbonate in the solvent is not particularly limited, the contentthereof is, for example, from 0.01 wt % to 50 wt % both inclusive.However, specific examples of the halogenated ester carbonate are notlimited to the compounds described below.

In Formula (6), each of R17 to R20 is one of a hydrogen group, a halogengroup, an alkyl group, and a halogenated alkyl group. One or more of R17to R20 are each one of a halogen group and a halogenated alkyl group.

In Formula (7), each of R21 to R26 is one of a hydrogen group, a halogengroup, an alkyl group, and a halogenated alkyl group. One or more of R21to R26 are each a halogen group or a halogenated alkyl group.

Although halogen type is not particularly limited, in particular,fluorine (F), chlorine (Cl), or bromine (Br) is preferable, and fluorineis more preferable since thereby, a higher effect is obtained comparedto other halogens. However, the number of halogens is more preferablytwo than one, and further may be three or more. One reason for this isthat, since thereby, an ability of forming a protective film isimproved, a more rigid and stable protective film is formed.

Examples of the halogenated cyclic ester carbonate include compoundsrepresented by the following Formula (6-1) to the following Formula(6-21). Such compounds include a geometric isomer. In particular,4-fluoro-1,3-dioxolane-2-one represented by Formula (6-1) or4,5-difluoro-1,3-dioxolane-2-one represented by Formula (6-3) ispreferable, and the latter is more preferable. Further, as4,5-difluoro-1,3-dioxolane-2-one, a trans isomer is more preferable thana cis isomer, since the trans isomer is easily available and provides ahigh effect. Examples of the halogenated chain ester carbonate includefluoromethyl methyl carbonate, bis(fluoromethyl) carbonate, anddifluoromethyl methyl carbonate.

Further, the solvent preferably contains sultone (cyclic sulfonicester), since the chemical stability of the electrolytic solution ismore improved thereby. Examples of sultone include propane sultone andpropene sultone. Although the sultone content in the solvent is notparticularly limited, for example, the sultone content is from 0.5 wt %to 5 wt % both inclusive. Specific examples of sultone are not limitedto the foregoing compounds.

Further, the solvent preferably contains an acid anhydride since thechemical stability of the electrolytic solution is thereby furtherimproved. Examples of the acid anhydrides include a carboxylicanhydride, a disulfonic anhydride, and a carboxylic acid sulfonic acidanhydride. Examples of the carboxylic anhydride include a succinicanhydride, a glutaric anhydride, and a maleic anhydride. Examples of thedisulfonic anhydride include an ethane disulfonic anhydride and apropane disulfonic anhydride. Examples of the carboxylic acid sulfonicacid anhydride include a sulfobenzoic anhydride, a sulfopropionicanhydride, and a sulfobutyric anhydride. Although the content of theacid anhydride in the solvent is not particularly limited, for example,the content thereof is from 0.5 wt % to 5 wt % both inclusive. However,specific examples of the acid anhydrides are not limited to theforegoing compounds.

The electrolyte salt used for the electrolytic solution may contain, forexample, one or more of salts such as a lithium salt. However, theelectrolyte salt may contain, for example, a salt other than the lithiumsalt (for example, a light metal salt other than the lithium salt).

Examples of the lithium salts include lithium hexafluorophosphate(LiPF₆), lithium tetrafluoroborate (LiBF₄), lithium perchlorate(LiClO₄), lithium hexafluoroarsenate (LiAsF₆), lithium tetraphenylborate(LiB(C₆H₅)₄), lithium methanesulfonate (LiCH₃SO₃), lithiumtrifluoromethane sulfonate (LiCF₃SO₃), lithium tetrachloroaluminate(LiAlCl₄), dilithium hexafluorosilicate (Li₂SiF₆), lithium chloride(LiCl), and lithium bromide (LiBr). Thereby, a superior batterycapacity, superior cycle characteristics, superior conservationcharacteristics, and the like are obtained. However, specific examplesof the lithium salt are not limited to the foregoing compounds, and maybe other compounds.

In particular, one or more of LiPF₆, LiBF₄, LiClO₄, and LiAsF₆ arepreferable, and LiPF₆ is more preferable, since the internal resistanceis thereby lowered, and therefore, a higher effect is obtained.

In particular, the electrolyte salt preferably contains one or more ofcompounds represented by the following Formula (8) to the followingFormula (10), since a higher effect is obtained thereby. It is to benoted that R31 and R33 may be the same type of group, or may be groupsdifferent from each other. The same is applied to R41 to R43 and to R51and R52. However, specific examples of the compounds represented byFormula (8) to Formula (10) are not limited to the after-mentionedcompounds.

In Formula (8), X31 is one of Group 1 elements, Group 2 elements in thelong-period periodic table, and Al. M31 is one of transition metals,Group 13 elements, Group 14 elements, and Group 15 elements in thelong-period periodic table. R31 is a halogen group. Y31 is one of—C(═O)—R32-C(═O)—, —C(═O)—CR33₂—, and —C(═O)—C(═O)—. R32 is one of analkylene group, a halogenated alkylene group, an arylene group, and ahalogenated arylene group. R33 is one of an alkyl group, a halogenatedalkyl group, an aryl group, and a halogenated aryl group. a3 is one ofinteger numbers 1 to 4 both inclusive. b3 is one of integer numbers 0,2, and 4. Each of c3, d3, m3, and n3 is one of integer numbers 1 to 3both inclusive.

In Formula (9), X41 is one of Group 1 elements and Group 2 elements inthe long-period periodic table. M41 is one of transition metals, Group13 elements, Group 14 elements, and Group 15 elements in the long-periodperiodic table. Y41 is one of —C(═O)—(CR41₂)_(b4)—C(═O)—,—R43₂C—(CR42₂)_(c4)-C(═O)—, —R43₂C—(CR42₂)_(c4)—CR43₂-,—R43₂C—(CR42₂)_(c4)—S(═O)₂—, —S(═O)₂—(CR42₂)_(d4)—S(═O)₂—, and—C(═O)—(CR42₂)_(d4)—S(═O)₂—. Each of R41 and R43 is one of a hydrogengroup, an alkyl group, a halogen group, and a halogenated alkyl group.One or more of R41 and R43 are each the halogen group or the halogenatedalkyl group. R42 is one of a hydrogen group, an alkyl group, a halogengroup, and a halogenated alkyl group. Each of a4, e4, and n4 is one ofinteger numbers 1 and 2. Each of b4 and d4 is one of integer numbers 1to 4 both inclusive. c4 is one of integer numbers 0 to 4 both inclusive.Each of f4 and m4 is one of integer numbers 1 to 3 both inclusive.

In Formula (10), X51 is one of Group 1 elements and Group 2 elements inthe long-period periodic table. M51 is one of transition metals, Group13 elements, Group 14 elements, and Group 15 elements in the long-periodperiodic table. Rf is one of a fluorinated alkyl group with carbonnumber from 1 to 10 both inclusive and a fluorinated aryl group withcarbon number from 1 to 10 both inclusive. Y51 is one of—C(═O)—(CR51₂)_(d5)—C(═O)—, —R52₂C—(CR51₂)_(d5)—C(═O)—,—R52₂C—(CR51₂)_(d5)—CR52₂—, —R52₂C—(CR51₂)_(d5)—S(═O)₂—,—S(═O)₂—(CR51₂)_(e5)—S(═O)₂—, and —C(═O)—(CR51₂)_(e5)—S(═O)₂—. R51 isone of a hydrogen group, an alkyl group, a halogen group, and ahalogenated alkyl group. R52 is one of a hydrogen group, an alkyl group,a halogen group, and a halogenated alkyl group, and one or more thereofare each a halogen group or a halogenated alkyl group. Each of a5, f5,and n5 is one of integer numbers 1 and 2. Each of b5, c5, and e5 is oneof integer numbers 1 to 4 both inclusive. d5 is one of integer numbers 0to 4 both inclusive. Each of g5 and m5 is one of integer numbers 1 to 3both inclusive.

It is to be noted that Group 1 elements include H, Li, Na, K, Rb, Cs,and Fr. Group 2 elements include Be, Mg, Ca, Sr, Ba, and Ra. Group 13elements include B, Al, Ga, In, and Tl. Group 14 elements include C, Si,Ge, Sn, and Pb. Group 15 elements include N, P, As, Sb, and Bi.

Examples of the compound represented by Formula (8) include compoundsrepresented by Formula (8-1) to Formula (8-6). Examples of the compoundrepresented by Formula (9) include compounds represented by Formula(9-1) to Formula (9-8). Examples of the compound represented by Formula(10) include a compound represented by Formula (10-1).

Further, the electrolyte salt preferably contains one or more ofcompounds represented by the following Formula (11) to the followingFormula (13), since a higher effect is obtained thereby. It is to benoted that m and n may be the same value or values different from eachother. The same is applied to p, q, and r. However, specific examples ofthe compounds represented by Formula (11) to Formula (13) are notlimited to compounds described below.

LiN(C_(m)F_(2m+1)SO₂)(C_(n)F_(2n+1)SO₂)  (11)

In Formula (11), each of m and n is an integer number equal to orgreater than 1.

In Formula (12), R61 is a straight-chain or branched perfluoro alkylenegroup with carbon number from 2 to 4 both inclusive.

LiC(C_(p)F_(2p+1)SO₂)(C_(q)F_(2q+1)SO₂)(C_(r)f_(2r+1)SO₂)  (13)

In Formula (13), each of p, q, and r is an integer number equal to orgreater than 1.

The compound represented by Formula (11) is a chain imide compound.Examples thereof include lithium bis(trifluoromethanesulfonyl)imide(LiN(CF₃SO₂)₂), lithium bis(pentafluoroethanesulfonyl)imide(LiN(C₂F₅SO₂)₂), lithium(trifluoromethanesulfonyl)(pentafluoroethanesulfonyl)imide(LiN(CF₃SO₂)(C₂F₅SO₂)),lithium(trifluoromethanesulfonyl)(heptafluoropropanesulfonyl)imide(LiN(CF₃SO₂)(C₃F₇SO₂)), andlithium(trifluoromethanesulfonyl)(nonafluorobutanesulfonyl)imide(LiN(CF₃SO₂)(C₄F₉SO₂)).

The compound represented by Formula (12) is a cyclic imide compound.Examples thereof include compounds represented by Formula (12-1) toFormula (12-4).

The compound represented by Formula (13) is a chain methyde compound.Examples thereof include lithium tris(trifluoromethanesulfonyl)methyde(LiC(CF₃SO₂)₃).

Although the content of the electrolyte salt is not particularlylimited, in particular, the content thereof is preferably from 0.3mol/kg to 3.0 mol/kg both inclusive with respect to the solvent, sincehigh ion conductivity is obtained thereby.

[Operation of Secondary Battery]

In the secondary battery, for example, at the time of charge, lithiumions extracted from the cathode 21 are inserted in the anode 22 throughthe electrolytic solution. Further, at the time of discharge, lithiumions extracted from the anode 22 are inserted in the cathode 21 throughthe electrolytic solution.

[Method of Manufacturing Secondary Battery]

The secondary battery is manufactured, for example, by the followingprocedure.

First, the cathode 21 is fabricated. A cathode active material is mixedwith a cathode binder, a cathode electric conductor, and/or the like asnecessary to prepare a cathode mixture. Subsequently, the cathodemixture is dispersed in an organic solvent or the like to obtain pastecathode mixture slurry. Subsequently, both surfaces of the cathodecurrent collector 21A are coated with the cathode mixture slurry, whichis dried to form the cathode active material layer 21B. In this case,the cathode active material layer 21B may be formed only on a singlesurface of the cathode current collector 21A. Subsequently, the cathodeactive material layer 21B is compression-molded by using a roll pressingmachine and/or the like while being heated as necessary. In this case,compression-molding may be repeated several times.

Further, the anode 22 is fabricated by a procedure similar to that ofthe cathode 21 described above. An anode active material is mixed withan anode binder, an anode electric conductor, and/or the like asnecessary to prepare an anode mixture, which is subsequently dispersedin an organic solvent or the like to form paste anode mixture slurry.Subsequently, a single surface or both surfaces of the anode currentcollector 22A are coated with the anode mixture slurry, which is driedto form the anode active material layer 22B. Thereafter, the anodeactive material layer 22B is compression-molded as necessary.

Further, after an electrolyte salt is dispersed in a solvent, anunsaturated cyclic ester carbonate is added thereto to prepare anelectrolytic solution.

Finally, the secondary battery is assembled by using the cathode 21 andthe anode 22. The cathode lead 25 is attached to the cathode currentcollector 21A by using a welding method and/or the like, and the anodelead 26 is attached to the anode current collector 22A by using awelding method and/or the like. Subsequently, the cathode 21 and theanode 22 are layered with the separator 23 in between and are spirallywound, and thereby, the spirally wound electrode body 20 is fabricated.Thereafter, the center pin 24 is inserted in the center of the spirallywound electrode body. Subsequently, the spirally wound electrode body 20is sandwiched between the pair of insulating plates 12 and 13, and iscontained in the battery can 11. In this case, the end tip of thecathode lead 25 is attached to the safety valve mechanism 15 by using awelding method and/or the like, and the end tip of the anode lead 26 isattached to the battery can 11 by using a welding method and/or thelike. Subsequently, the electrolytic solution is injected into thebattery can 11, and the separator 23 is impregnated with theelectrolytic solution. Subsequently, at the open end of the battery can11, the battery cover 14, the safety valve mechanism 15, and the PTCdevice 16 are fixed by being swaged with the gasket 17.

[Function and Effect of Secondary Battery]

According to the cylindrical-type secondary battery, the anode activematerial layer 22B contains a carbon material, the thickness of theanode active material layer 22B is equal to or larger than 30 μm, andthe electrolytic solution contains the unsaturated cyclic estercarbonate. In this case, as described above, the thickness of the anodeactive material layer 22B is appropriate on the relationship with thefunction of suppressing decomposition of the electrolytic solution bythe unsaturated cyclic ester carbonate. Therefore, the function ofsuppressing decomposition of the electrolytic solution by theunsaturated cyclic ester carbonate is effectively exercised. Thereby,chemical stability of the electrolytic solution is specificallyimproved, and therefore, a decomposition reaction of the electrolyticsolution is suppressed. Therefore, even if the secondary battery ischarged and discharged, or stored, the electrolytic solution is lesslikely to be decomposed, and accordingly, superior batterycharacteristics are obtainable.

In particular, in the case where the content of the unsaturated cyclicester carbonate in the electrolytic solution is from 0.01 wt % to 10 wt% both inclusive, higher effects are obtainable. Further, in the casewhere the unsaturated cyclic ester carbonate is one of the compoundsrepresented by Formula (1-1) to Formula (1-56), and in particular, isthe compound represented by Formula (2) or the compound represented byFormula (3), higher effects are obtainable. In addition thereto, in thecase where the volume density of the anode active material layer 22B isfrom 1.4 g/cm³ to 1.95 g/cm³ both inclusive, further higher effects areobtainable.

[1-2. Laminated Film Type]

FIG. 3 illustrates an exploded perspective configuration of anothersecondary battery according to the embodiment of the presentapplication. FIG. 4 illustrates an enlarged cross-section taken along aline IV-IV of a spirally wound electrode body 30 illustrated in FIG. 3.In the following description, the elements of the cylindrical-typesecondary battery described above will be used as necessary.

[Whole Configuration of Secondary Battery]

The secondary battery herein described is, for example, what we call alaminated-film-type lithium ion secondary battery. In the secondarybattery, the spirally wound electrode body 30 is contained in afilm-like outer package member 40. In the spirally wound electrode body30, a cathode 33 and an anode 34 are layered with a separator 35 and anelectrolyte layer 36 in between and are spirally wound. A cathode lead31 is attached to the cathode 33, and an anode lead 32 is attached tothe anode 34. The outermost periphery of the spirally wound electrodebody 30 is protected by a protective tape 37.

The cathode lead 31 and the anode lead 32 are, for example, led out frominside to outside of the outer package member 40 in the same direction.The cathode lead 31 is made of, for example, a conductive material suchas aluminum, and the anode lead 32 is made of, for example, a conducivematerial such as copper, nickel, and stainless steel. These conductivematerials are in the shape of, for example, a thin plate or mesh.

The outer package member 40 is a laminated film in which, for example, afusion bonding layer, a metal layer, and a surface protective layer arelaminated in this order. In the laminated film, for example, therespective outer edges of the fusion bonding layers of two films arebonded to each other by fusion bonding, so that the fusion bondinglayers and the spirally wound electrode body 30 are opposed to eachother. The two films may be attached to each other by an adhesive, orthe like. Examples of the fusion bonding layer include a film made ofpolyethylene, polypropylene, or the like. Examples of the metal layerinclude an aluminum foil. Examples of the surface protective layerinclude a film made of nylon, polyethylene terephthalate, or the like.

In particular, as the outer package member 40, an aluminum laminatedfilm in which a polyethylene film, an aluminum foil, and a nylon filmare laminated in this order is preferable. However, the outer packagemember 40 may be made of a laminated film having other laminatedstructure, a polymer film such as polypropylene, or a metal film.

An adhesive film 41 to protect from outside air intrusion is insertedbetween the outer package member 40 and the cathode lead 31 and betweenthe outer package member 40 and the anode lead 32. The adhesive film 41is made of a material having adhesion characteristics with respect tothe cathode lead 31 and the anode lead 32. Examples of the materialhaving adhesion characteristics include a polyolefin resin such aspolyethylene, polypropylene, modified polyethylene, and modifiedpolypropylene.

The cathode 33 has, for example, a cathode active material layer 33B ona single surface or both surfaces of a cathode current collector 33A.The anode 34 has, for example, an anode active material layer 34B on asingle surface or both surfaces of an anode current collector 34A. Theconfigurations of the cathode current collector 33A, the cathode activematerial layer 33B, the anode current collector 34A, and the anodeactive material layer 34B are similar to the configurations of thecathode current collector 21A, the cathode active material layer 21B,the anode current collector 22A, and the anode active material layer22B, respectively. That is, the anode active material layer 34B containsa carbon material. The thickness of the anode active material layer 34Bis equal to or larger than 30 μm, and is preferably from 30 μm to 100 μmboth inclusive. Further, the configuration of the separator 35 issimilar to the configuration of the separator 23.

In the electrolyte layer 36, an electrolytic solution is held by apolymer compound. The electrolyte layer 36 is what we call a gelelectrolyte, since thereby, high ion conductivity (for example, 1 mS/cmor more at room temperature) is obtained and liquid leakage of theelectrolytic solution is prevented. The electrolyte layer 36 may containother material such as an additive as necessary.

Examples of the polymer compound include one or more ofpolyacrylonitrile, polyvinylidene fluoride, polytetrafluoroethylene,polyhexafluoropropylene, polyethylene oxide, polypropylene oxide,polyphosphazene, polysiloxane, polyvinyl fluoride, polyvinyl acetate,polyvinyl alcohol, polymethacrylic acid methyl, polyacrylic acid,polymethacrylic acid, styrene-butadiene rubber, nitrile-butadienerubber, polystyrene, polycarbonate, and a copolymer of vinylidenefluoride and hexafluoro propylene. In particular, polyvinylidenefluoride or the copolymer of vinylidene fluoride and hexafluoropropylene is preferable, and polyvinylidene fluoride is more preferable,since such a polymer compound is electrochemically stable.

The composition of the electrolytic solution is similar to thecomposition of the electrolytic solution of the cylindrical-typesecondary battery. The electrolytic solution contains the unsaturatedcyclic ester carbonate. However, in the electrolyte layer 36 as a gelelectrolyte, the solvent of the electrolytic solution refers to a wideconcept including not only a liquid solvent but also a material havingion conductivity capable of dissociating the electrolyte salt.Therefore, in the case where a polymer compound having ion conductivityis used, the polymer compound is also included in the solvent.

It is to be noted that the electrolytic solution may be used as it isinstead of the gel electrolyte layer 36. In this case, the separator 35is impregnated with the electrolytic solution.

[Operation of Secondary Battery]

In the secondary battery, for example, at the time of charge, lithiumions extracted from the cathode 33 are inserted in the anode 34 throughthe electrolyte layer 36. In contrast, at the time of discharge, lithiumions extracted from the anode 34 are inserted in the cathode 33 throughthe electrolyte layer 36.

[Method of Manufacturing Secondary Battery]

The secondary battery including the gel electrolyte layer 36 ismanufactured, for example, by the following three types of procedures.

In the first procedure, the cathode 33 and the anode 34 are fabricatedby a fabrication procedure similar to that of the cathode 21 and theanode 22. In this case, the cathode 33 is fabricated by forming thecathode active material layer 33B on a single surface or both surfacesof the cathode current collector 33A, and the anode 34 is fabricated byforming the anode active material layer 34B on a single surface or bothsurfaces of the anode current collector 34A. Subsequently, a precursorsolution containing an electrolytic solution, a polymer compound, and asolvent such as an organic solvent is prepared. Thereafter, the cathode33 and the anode 34 are coated with the precursor solution to form thegel electrolyte layer 36. Subsequently, the cathode lead 31 is attachedto the cathode current collector 33A by using a welding method and/orthe like and the anode lead 32 is attached to the anode currentcollector 34A by using a welding method and/or the like. Subsequently,the cathode 33 and the anode 34 are layered with the separator 35 inbetween and are spirally wound to form the spirally wound electrode body30. Thereafter, the protective tape 37 is adhered to the outermostperiphery thereof. Subsequently, after the spirally wound electrode body30 is sandwiched between two pieces of film-like outer package members40, the outer edges of the outer package members 40 are bonded by athermal fusion bonding method and/or the like to enclose the spirallywound electrode body 30 into the outer package members 40. In this case,the adhesive films 41 are inserted between the cathode lead 31 and theouter package member 40 and between the anode lead 32 and the outerpackage member 40.

In the second procedure, the cathode lead 31 is attached to the cathode33, and the anode lead 32 is attached to the anode 34. Subsequently, thecathode 33 and the anode 34 are layered with the separator 35 in betweenand are spirally wound to fabricate a spirally wound body as a precursorof the spirally wound electrode body 30. Thereafter, the protective tape37 is adhered to the outermost periphery thereof. Subsequently, afterthe spirally wound body is sandwiched between two pieces of thefilm-like outer package members 40, the outermost peripheries except forone side are bonded by using a thermal fusion bonding method and/or thelike to obtain a pouched state, and the spirally wound body is containedin the pouch-like outer package member 40. Subsequently, a compositionfor electrolyte containing an electrolytic solution, a monomer as a rawmaterial for the polymer compound, a polymerization initiator, and othermaterials such as a polymerization inhibitor as necessary is prepared,which is injected into the pouch-like outer package member 40.Thereafter, the outer package member 40 is hermetically sealed by usinga thermal fusion bonding method and/or the like. Subsequently, themonomer is thermally polymerized, and thereby, a polymer compound isformed. Accordingly, the gel electrolyte layer 36 is formed.

In the third procedure, the spirally wound body is fabricated andcontained in the pouch-like outer package member 40 in a manner similarto that of the foregoing second procedure, except that the separator 35with both surfaces coated with a polymer compound is used. Examples ofthe polymer compound with which the separator 35 is coated include apolymer (a homopolymer, a copolymer, or a multicomponent copolymer)containing vinylidene fluoride as a component. Specific examples thereofinclude polyvinylidene fluoride, a binary copolymer containingvinylidene fluoride and hexafluoro propylene as components, and aternary copolymer containing vinylidene fluoride, hexafluoro propylene,and chlorotrifluoroethylene as components. In addition to the polymercontaining vinylidene fluoride as a component, other one or more polymercompounds may be used. Subsequently, an electrolytic solution isprepared and injected into the outer package member 40. Thereafter, theopening of the outer package member 40 is hermetically sealed by using athermal fusion bonding method and/or the like. Subsequently, theresultant is heated while a weight is applied to the outer packagemember 40, and the separator 35 is adhered to the cathode 33 and theanode 34 with the polymer compound in between. Thereby, the polymercompound is impregnated with the electrolytic solution, and accordingly,the polymer compound is gelated to form the electrolyte layer 36.

In the third procedure, swollenness of the secondary battery issuppressed more than in the first procedure. Further, in the thirdprocedure, the monomer as a raw material of the polymer compound, thesolvent, and the like are less likely to be left in the electrolytelayer 36 compared to in the second procedure. Therefore, the formationstep of the polymer compound is favorably controlled. Therefore,sufficient adhesion characteristics are obtained between the cathode 33,the anode 34, and the separator 35, and the electrolyte layer 36.

[Function and Effect of Secondary Battery]

According to the laminated-film-type secondary battery, the anode activematerial layer 34B contains a carbon material, the thickness of theanode active material layer 34B is equal to or larger than 30 μm, andthe electrolytic solution of the electrolyte layer 36 contains theunsaturated cyclic ester carbonate. Therefore, for a reason similar tothat of the cylindrical-type secondary battery, superior batterycharacteristics are obtainable. Other functions and other effects aresimilar to those of the cylindrical-type secondary battery.

[2. Applications of Secondary Battery]

Next, a description will be given of application examples of theforegoing secondary battery.

Applications of the secondary battery are not particularly limited aslong as the secondary battery is used for a machine, a device, aninstrument, an apparatus, a system (collective entity of a plurality ofdevices and the like), or the like that is allowed to use the secondarybattery as a driving electric power source, an electric power storagesource for electric power storage, or the like. In the case where thesecondary battery is used as an electric power source, the secondarybattery may be used as a main electric power source (electric powersource used preferentially), or an auxiliary electric power source(electric power source used instead of a main electric power source orused being switched from the main electric power source). In the lattercase, the main electric power source type is not limited to thesecondary battery.

Examples of applications of the secondary battery include electronicapparatuses (including portable electronic apparatuses) such as a videocamcoder, a digital still camera, a mobile phone, a notebook personalcomputer, a cordless phone, a headphone stereo, a portable radio, aportable television, and a personal digital assistant. Further examplesthereof include a mobile lifestyle electric appliance such as anelectric shaver; a memory device such as a backup electric power sourceand a memory card; an electric power tool such as an electric drill andan electric saw; a battery pack used as an electric power source of anotebook personal computer or the like; a medical electronic apparatussuch as a pacemaker and a hearing aid; an electric vehicle such as anelectric automobile (including a hybrid automobile); and an electricpower storage system such as a home battery system for storing electricpower for emergency or the like. It is needless to say that anapplication other than the foregoing applications may be adopted.

In particular, the secondary battery is effectively applicable to thebattery pack, the electric vehicle, the electric power storage system,the electric power tool, the electronic apparatus, or the like. In theseapplications, since superior battery characteristics are demanded, theperformance is effectively improved by using the secondary batteryaccording to the embodiment of the present application. It is to benoted that the battery pack is an electric power source using asecondary battery, and is what we call an assembled battery or the like.The electric vehicle is a vehicle that works (runs) by using a secondarybattery as a driving electric power source. As described above, anautomobile (such as a hybrid automobile) including a drive source otherthan a secondary battery may be included. The electric power storagesystem is a system using a secondary battery as an electric powerstorage source. For example, in a home electric power storage system,electric power is stored in the secondary battery as an electric powerstorage source, and the electric power is consumed as necessary.Thereby, home electric products and the like become usable. The electricpower tool is a tool in which a movable section (such as a drill) ismoved by using a secondary battery as a driving electric power source.The electronic apparatus is an apparatus executing various functions byusing a secondary battery as a driving electric power source (electricpower supply source).

A description will be specifically given of some application examples ofthe secondary battery. The configurations of the respective applicationexamples explained below are merely examples, and may be changed asappropriate.

[2-1. Battery Pack]

FIG. 5 illustrates a block configuration of a battery pack. For example,as illustrated in FIG. 5, the battery pack includes a control section61, an electric power source 62, a switch section 63, a currentmeasurement section 64, a temperature detection section 65, a voltagedetection section 66, a switch control section 67, a memory 68, atemperature detection device 69, a current detection resistance 70, acathode terminal 71, and an anode terminal 72 in a housing 60 made of aplastic material and/or the like.

The control section 61 controls operation of the whole battery pack(including a used state of the electric power source 62), and includes,for example, a central processing unit (CPU) and/or the like. Theelectric power source 62 includes one or more secondary batteries (notillustrated). The electric power source 62 is, for example, an assembledbattery including two or more secondary batteries. Connection typethereof may be a series-connected type, may be a parallel-connectedtype, or a mixed type thereof. As an example, the electric power source62 includes six secondary batteries connected in a manner ofdual-parallel and three-series.

The switch section 63 switches the used state of the electric powersource 62 (whether or not the electric power source 62 is connectable toan external device) according to an instruction of the control section61. The switch section 63 includes, for example, a charge controlswitch, a discharge control switch, a charging diode, a dischargingdiode, and the like (not illustrated). The charge control switch and thedischarge control switch are each, for example, a semiconductor switchsuch as a field-effect transistor (MOSFET) using a metal oxidesemiconductor.

The current measurement section 64 measures a current by using thecurrent detection resistance 70, and outputs the measurement result tothe control section 61. The temperature detection section 65 measurestemperature by using the temperature detection device 69, and outputsthe measurement result to the control section 61. The temperaturemeasurement result is used for, for example, a case in which the controlsection 61 controls charge and discharge at the time of abnormal heatgeneration or a case in which the control section 61 performs acorrection processing at the time of calculating a remaining capacity.The voltage detection section 66 measures a voltage of the secondarybattery in the electric power source 62, performs analog-to-digitalconversion (A/D conversion) on the measured voltage, and supplies theresultant to the control section 61.

The switch control section 67 controls operations of the switch section63 according to signals inputted from the current measurement section 64and the voltage measurement section 66.

The switch control section 67 executes control so that a charge currentis prevented from flowing in a current path of the electric power source62 by disconnecting the switch section 63 (charge control switch) in thecase where, for example, a battery voltage reaches an overchargedetection voltage. Thereby, in the electric power source 62, onlydischarge is allowed to be performed through the discharging diode. Itis to be noted that, for example, in the case where a large currentflows at the time of charge, the switch control section 67 blocks thecharge current.

Further, the switch control section 67 executes control so that adischarge current is prevented from flowing in the current path of theelectric power source 62 by disconnecting the switch section 63(discharge control switch) in the case where, for example, a batteryvoltage reaches an overdischarge detection voltage. Thereby, in theelectric power source 62, only charge is allowed to be performed throughthe charging diode. For example, in the case where a large current flowsat the time of discharge, the switch control section 67 blocks thedischarge current.

It is to be noted that, in the secondary battery, for example, theovercharge detection voltage is 4.2 V±0.05 V, and the over-dischargedetection voltage is 2.4 V±0.1 V.

The memory 68 is, for example, an EEPROM as a nonvolatile memory or thelike. The memory 68 stores, for example, numerical values calculated bythe control section 61 and information of the secondary battery measuredin a manufacturing step (such as an internal resistance in the initialstate). It is to be noted that, in the case where the memory 68 stores afull charge capacity of the secondary battery, the control section 61 isallowed to comprehend information such as a remaining capacity.

The temperature detection device 69 measures temperature of the electricpower source 62, and outputs the measurement result to the controlsection 61. The temperature detection device 69 is, for example, athermistor or the like.

The cathode terminal 71 and the anode terminal 72 are terminalsconnected to an external device (such as a notebook personal computer)driven by using the battery pack or an external device (such as abattery charger) used for charging the battery pack. The electric powersource 62 is charged and discharged through the cathode terminal 71 andthe anode terminal 72.

[2-2. Electric Vehicle]

FIG. 6 illustrates a block configuration of a hybrid automobile as anexample of electric vehicles. For example, as illustrated in FIG. 6, theelectric vehicle includes a control section 74, an engine 75, anelectric power source 76, a driving motor 77, a differential 78, anelectric generator 79, a transmission 80, a clutch 81, inverters 82 and83, and various sensors 84 in a housing 73 made of metal. In additionthereto, the electric vehicle includes, for example, a front drive shaft85 and a front tire 86 that are connected to the differential 78 and thetransmission 80, a rear drive shaft 87, and a rear tire 88.

The electric vehicle is runnable by using one of the engine 75 and themotor 77 as a drive source. The engine 75 is a main power source, andis, for example, a petrol engine. In the case where the engine 75 isused as a power source, drive power (torque) of the engine 75 istransferred to the front tire 86 or the rear tire 88 through thedifferential 78, the transmission 80, and the clutch 81 as drivesections, for example. The torque of the engine 75 is also transferredto the electric generator 79. Due to the torque, the electric generator79 generates alternating-current electric power. The alternating-currentelectric power is converted into direct-current electric power throughthe inverter 83, and the converted power is stored in the electric powersource 76. On the other hand, in the case where the motor 77 as aconversion section is used as a power source, electric power(direct-current electric power) supplied from the electric power source76 is converted into alternating-current electric power through theinverter 82. The motor 77 is driven by the alternating-current electricpower. Drive power (torque) obtained by converting the electric power bythe motor 77 is transferred to the front tire 86 or the rear tire 88through the differential 78, the transmission 80, and the clutch 81 asthe drive sections, for example.

It is to be noted that, alternatively, the following mechanism may beadopted. In the mechanism, in the case where speed of the electricvehicle is reduced by an unillustrated brake mechanism, the resistanceat the time of speed reduction is transferred to the motor 77 as torque,and the motor 77 generates alternating-current electric power by thetorque. It is preferable that the alternating-current electric power beconverted to direct-current electric power through the inverter 82, andthe direct-current regenerative electric power be stored in the electricpower source 76.

The control section 74 controls operations of the whole electricvehicle, and, for example, includes a CPU and/or the like. The electricpower source 76 includes one or more secondary batteries (notillustrated). Alternatively, the electric power source 76 may beconnected to an external electric power source, and electric power maybe stored by receiving the electric power from the external electricpower source. The various sensors 84 are used, for example, forcontrolling the number of revolutions of the engine 75 or forcontrolling opening level (throttle opening level) of an unillustratedthrottle valve. The various sensors 84 include, for example, a speedsensor, an acceleration sensor, an engine frequency sensor, and/or thelike.

The description has been hereinbefore given of the hybrid automobile asan electric vehicle. However, examples of the electric vehicles mayinclude a vehicle (electric automobile) working by using only theelectric power source 76 and the motor 77 without using the engine 75.

[2-3. Electric Power Storage System]

FIG. 7 illustrates a block configuration of an electric power storagesystem. For example, as illustrated in FIG. 7, the electric powerstorage system includes a control section 90, an electric power source91, a smart meter 92, and a power hub 93 inside a house 89 such as ageneral residence and a commercial building.

In this case, the electric power source 91 is connected to, for example,an electric device 94 arranged inside the house 89, and is connectableto an electric vehicle 96 parked outside the house 89. Further, forexample, the electric power source 91 is connected to a private powergenerator 95 arranged inside the house 89 through the power hub 93, andis connectable to an external concentrating electric power system 97thorough the smart meter 92 and the power hub 93.

It is to be noted that the electric device 94 includes, for example, oneor more home electric appliances such as a refrigerator, an airconditioner, a television, and a water heater. The private powergenerator 95 is, for example, one or more of a solar power generator, awind-power generator, and the like. The electric vehicle 96 is, forexample, one or more of an electric automobile, an electric motorcycle,a hybrid automobile, and the like. The concentrating electric powersystem 97 is, for example, one or more of a thermal power plant, anatomic power plant, a hydraulic power plant, a wind-power plant, and thelike.

The control section 90 controls operations of the whole electric powerstorage system (including a used state of the electric power source 91),and, for example, includes a CPU and/or the like. The electric powersource 91 includes one or more secondary batteries (not illustrated).The smart meter 92 is, for example, an electric power meter compatiblewith a network arranged in the house 89 demanding electric power, and iscommunicable with an electric power supplier. Accordingly, for example,while the smart meter 92 communicates with outside as necessary, thesmart meter 92 controls the balance between supply and demand in thehouse 89 and allows effective and stable energy supply.

In the electric power storage system, for example, electric power isstored in the electric power source 91 from the concentrating electricpower system 97 as an external electric power source through the smartmeter 92 and the power hub 93, and electric power is stored in theelectric power source 91 from the private power generator 95 as anindependent electric power source through the power hub 93. Asnecessary, the electric power stored in the electric power source 91 issupplied to the electric device 94 or to the electric vehicle 96according to an instruction of the control section 90. Therefore, theelectric device 94 becomes operable, and the electric vehicle 96 becomeschargeable. That is, the electric power storage system is a systemcapable of storing and supplying electric power in the house 89 by usingthe electric power source 91.

The electric power stored in the electric power source 91 is arbitrarilyusable. Therefore, for example, electric power is allowed to be storedin the electric power source 91 from the concentrating electric powersystem 97 in the middle of the night when an electric rate isinexpensive, and the electric power stored in the electric power source91 is allowed to be used during daytime hours when an electric rate isexpensive.

The foregoing electric power storage system may be arranged for eachhousehold (family unit), or may be arranged for a plurality ofhouseholds (family units).

[2-4. Electric Power Tool]

FIG. 8 illustrates a block configuration of an electric power tool. Forexample, as illustrated in FIG. 8, the electric power tool is anelectric drill, and includes a control section 99 and an electric powersource 100 in a tool body 98 made of a plastic material and/or the like.For example, a drill section 101 as a movable section is attached to thetool body 98 in an operable (rotatable) manner.

The control section 99 controls operations of the whole electric powertool (including a used state of the electric power source 100), andincludes, for example, a CPU and/or the like. The electric power source100 includes one or more secondary batteries (not illustrated). Thecontrol section 99 executes control so that electric power is suppliedfrom the electric power source 100 to the drill section 101 as necessaryaccording to operation of an unillustrated operation switch to operatethe drill section 101.

EXAMPLES

Specific Examples according to the embodiment of the present applicationwill be described in detail.

Examples 1-1 to 1-22

The cylindrical-type lithium ion secondary battery illustrated in FIG. 1and FIG. 2 was fabricated by the following procedure.

In fabricating the cathode 21, first, lithium carbonate (Li₂CO₃) andcobalt carbonate (CoCO₃) were mixed at a molar ratio ofLi₂CO₃:CoCO₃=0.5:1. Subsequently, the mixture was fired in the air (900deg C. for 5 hours). Thereby, lithium-cobalt composite oxide (LiCoO₂)was obtained. Subsequently, 94 parts by mass of a cathode activematerial (LiCoO₂), 3 parts by mass of a cathode binder (polyvinylidenefluoride: PVDF), and 3 parts by mass of a cathode electric conductor(graphite) were mixed to obtain a cathode mixture. Subsequently, thecathode mixture was dispersed in an organic solvent(N-methyl-2-pyrrolidone: NMP) to obtain a paste cathode mixture slurry.Subsequently, both surfaces of the cathode current collector 21A in theshape of a strip (aluminum foil being 10 μm thick) were coated with thecathode mixture slurry uniformly by using a coating device, which wasdried to form the cathode active material layer 21B. Finally, thecathode active material layer 21B was compression-molded by using a rollpressing machine.

In fabricating the anode 22, 90 parts by mass of an anode activematerial (artificial graphite) and 10 parts by mass of an anode binder(PVDF) were mixed to obtain an anode mixture. Subsequently, the anodemixture was dispersed in an organic solvent (NMP) to obtain a pasteanode mixture slurry. Subsequently, both surfaces of the anode currentcollector 22A in the shape of a strip (electrolytic copper foil being 10μm thick) were coated with the anode mixture slurry uniformly by using acoating device, which was dried to form the anode active material layer22B. Finally, the anode active material layer 22B was compression-moldedby using a roll pressing machine. In forming the anode active materiallayer 22B, as illustrated in table 1, the thickness (μm) of the anodeactive material layer 22B on a single surface side of the anode currentcollector 22A and the volume density thereof (g/cm³) were adjustedaccording to the coating amount of the anode mixture slurry and thepress pressure.

In preparing an electrolytic solution, an electrolyte salt (LiPF₆) wasdissolved in a solvent (ethylene carbonate (EC) and dimethyl carbonate(DMC)). Thereafter, as illustrated in Table 1, as necessary, anunsaturated cyclic ester carbonate was added thereto. In this case, thecomposition of the solvent was EC:DMC=50:50 at a weight ratio, and thecontent of the electrolyte salt with respect to the solvent was 1mol/kg.

In assembling the secondary battery, first, the cathode lead 25 made ofaluminum was welded to the cathode current collector 21A, and the anodelead 26 made of nickel was welded to the anode current collector 22A.Subsequently, the cathode 21 and the anode 22 were layered with theseparator 23 (microporous polypropylene film being 25 μm thick) inbetween and were spirally wound. Thereafter, the winding end section wasfixed by using an adhesive tape to fabricate the spirally woundelectrode body 20. Subsequently, the center pin 24 was inserted in thecenter of the spirally wound electrode body 20. Subsequently, while thespirally wound electrode body 20 was sandwiched between the pair ofinsulating plates 12 and 13, the spirally wound electrode body 20 wascontained in the battery can 11 made of iron and plated with nickel. Inthis case, one end of the cathode lead 25 was welded to the safety valvemechanism 15, and one end of the anode lead 26 was welded to the batterycan 11. Subsequently, the electrolytic solution was injected into thebattery can 11 by a depressurization method, and the separator 23 wasimpregnated with the electrolytic solution. Finally, at the open end ofthe battery can 11, the battery cover 14, the safety valve mechanism 15,and the PTC device 16 were fixed by being swaged with the gasket 17. Thecylindrical-type secondary battery was thereby completed. In fabricatingthe secondary battery, lithium metal was prevented from beingprecipitated on the anode 22 at the time of full charge by adjusting thethickness of the cathode active material layer 21B.

Battery characteristics (cycle characteristics and conservationcharacteristics) of the secondary battery were examined. Resultsillustrated in Table 1 were obtained.

In examining the cycle characteristics, one cycle of charge anddischarge was performed on the secondary battery in the ambienttemperature environment (23 deg C.) to stabilize the battery state.Thereafter, another one cycle of charge and discharge was performed onthe secondary battery in the same environment, and a discharge capacitywas measured. Subsequently, the secondary battery was repeatedly chargedand discharged until the total number of cycles reached 300 in the sameenvironment, and a discharge capacity was measured. From these results,cycle retention ratio (%)=(discharge capacity at the 300thcycle/discharge capacity at the second cycle)×100 was calculated. At thetime of charge, charge was performed at a current of 1 C until thevoltage reached the upper limit voltage of 4.2 V, and further charge wasperformed at a constant voltage until the total time from startingcharge reached 3 hours. At the time of discharge, discharge wasperformed at a current of 1 C until the voltage reached the finalvoltage of 3 V. “1C” is a current value at which the battery capacity(theoretical capacity) is fully discharged in 1 hour.

In examining the conservation characteristics, a secondary battery withits battery state stabilized by a procedure similar to that in the caseof examining the cycle characteristics was used. One cycle of charge anddischarge was performed on the secondary battery in the ambienttemperature environment (23 deg C.), and a discharge capacity wasmeasured. Subsequently, the secondary battery in a state of beingcharged again was stored in a constant temperature bath (80 deg C.) for10 days. Thereafter, the secondary battery was discharged in the ambienttemperature environment (23 deg C.), and a discharge capacity wasmeasured. From these results, conservation retention ratio(%)=(discharge capacity after storage/discharge capacity beforestorage)×100 was calculated. The charge and discharge conditions aresimilar to those in the case of examining the cycle characteristics.

It is to be noted that parenthetic numerical values described in thecolumns of cycle retention ratio and conservation retention ratio inTable 1 and the other tables following Table 1 represent variable valuesresulting from presence or absence of the unsaturated cyclic estercarbonate in the electrolytic solution. Each of the variable values iscalculated based on, variable value (%)=(value in the case where theunsaturated cyclic ester carbonate is contained in the electrolyticsolution-value in the case where the unsaturated cyclic ester carbonateis not contained in the electrolytic solution).

TABLE 1 Anode active material: artificial graphite; Rating capacity:2600 m Ah Electrolytic solution Anode Unsaturated cyclic CycleConservation Thickness Volume Electrolyte ester carbonate retentionretention Example (μm) density (g/cm³) salt Solvent Type Content (wt %)ratio (%) ratio (%) 1-1 50 1.85 LiPF₆ EC + Formula 0.01 70 (+5)  82 (+1)1-2 DMC (1-1) 0.1 72 (+7)  83 (+2) 1-3 0.5 75 (+10) 85 (+4) 1-4 1 80(+15) 86 (+5) 1-5 2 82 (+17) 87 (+6) 1-6 5 80 (+15) 90 (+9) 1-7 10 70(+5)  88 (+7) 1-8 30 1.85 LiPF₆ EC + Formula 2 93 (+8)  90 (+5) 1-9 40DMC (1-1) 88 (+14) 88 (+5) 1-10 60 72 (+28) 87 (+7) 1-11 100 50 (+40) 85(+9) 1-12 50 1.85 LiPF₆ EC + Formula 2 78 (+13) 83 (+2) DMC (1-4) 1-13Formula 2 80 (+15) 85 (+4) (1-16) 1-14 Formula 2 77 (+12) 83 (+2) (1-18)1-15 Formula 2 78 (+13) 84 (+3) (1-32) 1-16 20 1.85 LiPF₆ EC + — — 90 901-17 DMC Formula 2 90 (+0)  90 (+0) (1-1) 1-18 30 — — 85 85 1-19 40 7483 1-20 50 65 81 1-21 60 44 80 1-22 100 10 76

In the case where the anode active material layer 22B contained thecarbon material (artificial graphite), the battery characteristicsshowed a specific tendency according to a relation between the thicknessof the anode active material layer 22B and presence or absence of theunsaturated cyclic ester carbonate in the electrolytic solution.

More specifically, in the case where the thickness of the anode activematerial layer 22B was less than 30 μm, even if the electrolyticsolution contained the unsaturated cyclic ester carbonate, the cycleretention ratio and the conservation retention ratio were not changed.One reason for this result may be as follows. In the case where thethickness of the anode active material layer 22B is small, adecomposition reaction of the electrolytic solution resulting fromfactors such as reactivity of the carbon material is less likely toproceed inherently. Therefore, in this case, the function of suppressingdecomposition of the electrolytic solution by the unsaturated cyclicester carbonate is not substantially exercised.

On the other hand, in the case where the thickness of the anode activematerial layer 22B was equal to or larger than 30 μm, and morespecifically, was from 30 μm to 100 μm both inclusive, when theelectrolytic solution contained the unsaturated cyclic ester carbonate,the cycle retention ratio was increased. One reason for this result maybe as follows. In the case where the thickness of the anode activematerial layer 22B is large, a decomposition reaction of theelectrolytic solution resulting from factors such as reactivity of thecarbon material easily proceeds inherently. Therefore, in this case, thefunction of suppressing decomposition of the electrolytic solution bythe unsaturated cyclic ester carbonate is effectively exercised.

In particular, in the case where the thickness of the anode activematerial layer 22B was equal to or larger than 30 μm, and theelectrolytic solution contained the unsaturated cyclic ester carbonate,if the content of the unsaturated cyclic ester carbonate was from 0.01wt % to 10 wt % both inclusive, a high cycle retention ratio and a highconservation retention ratio were obtained.

Further, in the case where the content of the unsaturated cyclic estercarbonate was from 0.5 wt % to 10 wt % both inclusive, the cycleretention ratio and the conservation retention ratio were furtherincreased.

Examples 2-1 to 2-9

Secondary batteries were fabricated by a procedure similar to that ofExample 1-5, except that the composition of the solvent was changed asillustrated in Table 2, and the respective characteristics wereexamined.

In this case, newly used solvents are as follows. As other unsaturatedcyclic ester carbonate, vinylene carbonate (VC) was used. As halogenatedester carbonates, 4-fluoro-1,3-dioxolane-2-one (FEC),trans-4,5-difluoro-1,3-dioxolane-2-one (t-DFEC), andbis(fluoromethyl)carbonate (DFDMC) were used. As sultone, propenesultone (PRS) was used. As acid anhydrides, succinic anhydride (SCAH)and sulfopropionic anhydride (PSAH) were used.

The content of VC in the solvent was 2 wt %, the content of FEC, t-DFEC,or DFDMC in the solvent was 5 wt %, and the content of PRS, SCAH, orPSAH in the solvent was 1 wt %.

TABLE 2 Anode active material: artificial graphite; Rating capacity:2600 m Ah Electrolytic solution Anode Unsaturated cyclic CycleConservation Thickness Volume Electrolyte ester carbonate retentionretention Example (μm) density (g/cm³) salt Solvent Type Content (wt %)ratio (%) ratio (%) 2-1 50 1.85 LiPF₆ EC + VC Formula 2 90 (+25) 90 (+9)2-2 DMC FEC (1-1) 92 (+27) 89 (+8) 2-3 t-DFEC 88 (+23) 88 (+7) 2-4 DFDMC90 (+25) 88 (+7) 2-5 PRS 85 (+20)  92 (+11) 2-6 SCAH 90 (+25) 90 (+9)2-7 PSAH 90 (+25)  95 (+14) 2-8 50 1.85 LiPF₆ EC + VC — — 70 83 2-9 DMCFEC 80 82

Even if the composition of the solvent was changed, high cycle retentionratios and high conservation retention ratios were obtained. Inparticular, in the case where the electrolytic solution contained otherunsaturated cyclic ester carbonate, the halogenated ester carbonate, thesultone, or the acid anhydride, the cycle retention ratio and theconservation retention ratio were further increased.

Examples 3-1 to 3-3

Secondary batteries were fabricated by a procedure similar to that ofExample 1-5 except that the composition of the electrolyte salt waschanged as illustrated in Table 3, and the respective characteristicswere examined.

In this case, newly used electrolyte salts were lithiumtetrafluoroborate (LiBF₄), bis[oxalato-O,O′] lithium borate (LiBOB)represented by Formula (8-6), and bis(trifluoromethanesulfonyl)imidelithium (LiN(CF₃SO₂)₂:LiTFSI). The content of LiPF₆ with respect to thesolvent was 0.9 mol/kg, and the content of LiBF₄ etc. with respect tothe solvent was 0.1 mol/kg.

TABLE 3 Anode active material: artificial graphite; Rating capacity:2600 m Ah Electrolytic solution Anode Unsaturated cyclic CycleConservation Thickness Volume Electrolyte ester carbonate retentionretention Example (μm) density (g/cm³) salt Solvent Type Content (wt %)ratio (%) ratio (%) 3-1 50 1.85 LiPF₆ LiBF₄ EC + Formula 2 83 (+18) 90(+9) 3-2 LiBOB DMC (1-1) 84 (+19) 90 (+9) 3-3 LiTFSI 83 (+18) 90 (+9)

Even if the composition of the electrolyte salt was changed, high cycleretention ratios and high conservation retention ratios were obtained.In particular, in the case where the electrolytic solution containedother electrolyte salt such as LiBF₄, the cycle retention ratio and theconservation retention ratio were further increased.

Examples 4-1 to 4-6

Secondary batteries were fabricated by a procedure similar to those ofExamples 1-5 and 1-20 except that the volume density of the anode activematerial layer 22B was changed as illustrated in Table 4, and therespective characteristics were examined.

TABLE 4 Anode active material: artificial graphite Electrolytic solutionAnode Unsaturated cyclic Rating Cycle Conservation Thickness VolumeElectrolyte ester carbonate capacity retention retention Example (μm)density (g/cm³) salt Solvent Type Content (wt %) (mAh) ratio (%) ratio(%) 4-1 50 1.4 LiPF₆ EC + Formula 2 2300 94 (+6)  79 (+4) 4-2 1.6 DMC(1-1) 2450 90 (+10) 87 (+5) 4-3 1.95 2650 56 (+14) 82 (+4) 4-4 50 1.4LiPF₆ EC + — — 2300 88 75 4-5 1.6 DMC 2450 80 82 4-6 1.95 2650 42 78

Even if the volume density was changed, results similar to those inTable 1 were obtained. In particular, in the case where the volumedensity was from 1.4 g/cm³ to 1.95 g/cm³ both inclusive, a high cycleretention ratio and a high conservation retention ratio were obtained.

From the results of Table 1 to Table 4, in the case where the anodeactive material layer contained a carbon material, the thickness of theanode active material layer was from 30 μm to 100 μm both inclusive, andthe electrolytic solution contained the unsaturated cyclic estercarbonate, superior battery characteristics were obtained.

The present application has been described with reference to theembodiment and Examples. However, the present application is not limitedto the examples described in the embodiment and Examples, and variousmodifications may be made. For example, the description has been givenof the lithium ion secondary battery as a secondary battery type.However, applicable secondary battery type is not limited thereto. Thesecondary battery of the present application is similarly applicable toa secondary battery in which the anode capacity includes a capacity dueto inserting and extracting lithium ions and a capacity associated withprecipitation and dissolution of lithium metal, and the battery capacityis expressed by the sum of these capacities. In this case, an anodematerial capable of inserting and extracting lithium ions is used as ananode active material, and the chargeable capacity of the anode materialis set to a smaller value than the discharge capacity of the cathode.

Further, the description has been given with the specific examples ofthe case in which the battery structure is the cylindrical type or thelaminated film type, and the battery device has the spirally woundstructure. However, applicable structures are not limited thereto. Thesecondary battery of the present application is similarly applicable toa battery having other battery structure such as a square-type battery,a coin-type battery, and a button-type battery or a battery in which thebattery device has other structure such as a laminated structure.

Further, the description has been given of the case using Li as anelectrode reactant. However, the electrode reactant is not necessarilylimited thereto. As an electrode reactant, for example, other Group 1element such as Na and K, a Group 2 element such as Mg and Ca, or otherlight metal such as Al may be used. The effect of the presentapplication may be obtained without depending on the electrode reactanttype, and therefore, even if the electrode reactant type is changed, asimilar effect is obtainable.

Further, with regard to the content of the unsaturated cyclic estercarbonate, the description has been given of the appropriate rangederived from the results of Examples. However, the description does nottotally deny a possibility that the content is out of the foregoingrange. That is, the foregoing appropriate range is a range particularlypreferable for obtaining the effects of the present application.Therefore, as long as the effects of the present application areobtained, the content may be out of the foregoing range in some degrees.

It is possible to achieve at least the following configurations from theabove-described exemplary embodiment and the modifications of thedisclosure.

(1) A secondary battery including:

a cathode;

an anode; and

an electrolytic solution, wherein

the anode includes an anode active material layer on an anode currentcollector,

the anode active material layer includes a carbon material,

the anode active material layer has a thickness from about 30micrometers to about 100 micrometers both inclusive, and

the electrolytic solution includes an unsaturated cyclic ester carbonaterepresented by the following Formula (1),

where X is a divalent group in which m-number of >C═CR1R2 and n-numberof >CR3R4 are bonded in any order; each of R1 to R4 is one of a hydrogengroup, a halogen group, a monovalent hydrocarbon group, a monovalenthalogenated hydrocarbon group, a monovalent oxygen-containinghydrocarbon group, and a monovalent halogenated oxygen-containinghydrocarbon group; any two or more of the R1 to the R4 are allowed to bebonded to one another; and m and n satisfy m≧1 and n≧0.(2) The secondary battery according to (1), wherein

the halogen group includes a fluorine group, a chlorine group, a brominegroup, and an iodine group, and

the monovalent hydrocarbon group, the monovalent halogenated hydrocarbongroup, the monovalent oxygen-containing hydrocarbon group, and themonovalent halogenated oxygen-containing hydrocarbon group include analkyl group with carbon number from 1 to 12 both inclusive, an alkenylgroup with carbon number from 2 to 12 both inclusive, an alkynyl groupwith carbon number from 2 to 12 both inclusive, an aryl group withcarbon number from 6 to 18 both inclusive, a cycloalkyl group withcarbon number from 3 to 18 both inclusive, an alkoxy group with carbonnumber from 1 to 12 both inclusive, a group obtained by bonding two ormore thereof, and a group obtained by substituting each of part or allof hydrogen groups thereof by a halogen group.

(3) The secondary battery according to (1) or (2), wherein theunsaturated cyclic ester carbonate is represented by one of thefollowing Formula (2) and the following Formula (3),

where each of R5 to R10 is one of a hydrogen group, a halogen group, amonovalent hydrocarbon group, a monovalent halogenated hydrocarbongroup, a monovalent oxygen-containing hydrocarbon group, and amonovalent halogenated oxygen-containing hydrocarbon group; the R5 andthe R6 are allowed to be bonded to each other; and any two or more ofthe R7 to the R10 are allowed to be bonded to one another.(4) The secondary battery according to any one of (1) to (3), whereinthe unsaturated cyclic ester carbonate is represented by one of thefollowing Formula (1-1) to the following Formula (1-56),

(5) The secondary battery according to any one of (1) to (4), wherein acontent of the unsaturated cyclic ester carbonate in the electrolyticsolution is from about 0.01 weight percent to about 10 weight percentboth inclusive.(6) The secondary battery according to any one of (1) to (5), whereinvolume density of the anode active material layer is from about 1.4grams per cubic centimeter to about 1.95 grams per cubic centimeter bothinclusive.(7) The secondary battery according to any one of (1) to (6), whereinthe secondary battery is a lithium ion secondary battery.(8) A battery pack including:

the secondary battery according to any one of (1) to (7);

a control section controlling a used state of the secondary battery; and

a switch section switching the used state of the secondary batteryaccording to an instruction of the control section.

(9) An electric vehicle including:

the secondary battery according to any one of (1) to (7);

a conversion section converting electric power supplied from thesecondary battery into drive power;

a drive section operating according to the drive power; and

a control section controlling a used state of the secondary battery.

(10) An electric power storage system including:

the secondary battery according to any one of (1) to (7);

one or more electric devices supplied with electric power from thesecondary battery; and

a control section controlling the supplying of the electric power fromthe secondary battery to the one or more electric devices.

(11) An electric power tool including:

the secondary battery according to any one of (1) to (7); and

a movable section being supplied with electric power from the secondarybattery.

(12) An electronic apparatus including the secondary battery accordingto any one of (1) to (7) as an electric power supply source.

It should be understood that various changes and modifications to thepresently preferred embodiments described herein will be apparent tothose skilled in the art. Such changes and modifications can be madewithout departing from the spirit and scope of the present subjectmatter and without diminishing its intended advantages. It is thereforeintended that such changes and modifications be covered by the appendedclaims.

The invention is claimed as follows:
 1. A secondary battery comprising:a cathode; an anode; and an electrolytic solution, wherein the anodeincludes an anode active material layer on an anode current collector,the anode active material layer includes a carbon material, the anodeactive material layer has a thickness from about 30 micrometers to about100 micrometers both inclusive, and the electrolytic solution includesan unsaturated cyclic ester carbonate represented by the followingFormula (1),

where X is a divalent group in which m-number of >C═CR1R2 and n-numberof >CR3R4 are bonded in any order; each of R1 to R4 is one of a hydrogengroup, a halogen group, a monovalent hydrocarbon group, a monovalenthalogenated hydrocarbon group, a monovalent oxygen-containinghydrocarbon group, and a monovalent halogenated oxygen-containinghydrocarbon group; any two or more of the R1 to the R4 are allowed to bebonded to one another; and m and n satisfy m≧1 and n≧0.
 2. The secondarybattery according to claim 1, wherein the halogen group includes afluorine group, a chlorine group, a bromine group, and an iodine group,and the monovalent hydrocarbon group, the monovalent halogenatedhydrocarbon group, the monovalent oxygen-containing hydrocarbon group,and the monovalent halogenated oxygen-containing hydrocarbon groupinclude an alkyl group with carbon number from 1 to 12 both inclusive,an alkenyl group with carbon number from 2 to 12 both inclusive, analkynyl group with carbon number from 2 to 12 both inclusive, an arylgroup with carbon number from 6 to 18 both inclusive, a cycloalkyl groupwith carbon number from 3 to 18 both inclusive, an alkoxy group withcarbon number from 1 to 12 both inclusive, a group obtained by bondingtwo or more thereof, and a group obtained by substituting each of partor all of hydrogen groups thereof by a halogen group.
 3. The secondarybattery according to claim 1, wherein the unsaturated cyclic estercarbonate is represented by one of the following Formula (2) and thefollowing Formula (3),

where each of R5 to R10 is one of a hydrogen group, a halogen group, amonovalent hydrocarbon group, a monovalent halogenated hydrocarbongroup, a monovalent oxygen-containing hydrocarbon group, and amonovalent halogenated oxygen-containing hydrocarbon group; the R5 andthe R6 are allowed to be bonded to each other; and any two or more ofthe R7 to the R10 are allowed to be bonded to one another.
 4. Thesecondary battery according to claim 1, wherein the unsaturated cyclicester carbonate is represented by one of the following Formula (1-1) tothe following Formula (1-56),


5. The secondary battery according to claim 1, wherein a content of theunsaturated cyclic ester carbonate in the electrolytic solution is fromabout 0.01 weight percent to about 10 weight percent both inclusive. 6.The secondary battery according to claim 1, wherein volume density ofthe anode active material layer is from about 1.4 grams per cubiccentimeter to about 1.95 grams per cubic centimeter both inclusive. 7.The secondary battery according to claim 1, wherein the secondarybattery is a lithium ion secondary battery.
 8. A battery packcomprising: a secondary battery; a control section controlling a usedstate of the secondary battery; and a switch section switching the usedstate of the secondary battery according to an instruction of thecontrol section, wherein the secondary battery includes a cathode, ananode, and an electrolytic solution, the anode includes an anode activematerial layer on an anode current collector, the anode active materiallayer includes a carbon material, the anode active material layer has athickness from about 30 micrometers to about 100 micrometers bothinclusive, and the electrolytic solution includes an unsaturated cyclicester carbonate represented by the following Formula (1),

where X is a divalent group in which m-number of >C═CR1R2 and n-numberof >CR3R4 are bonded in any order; each of R1 to R4 is one of a hydrogengroup, a halogen group, a monovalent hydrocarbon group, a monovalenthalogenated hydrocarbon group, a monovalent oxygen-containinghydrocarbon group, and a monovalent halogenated oxygen-containinghydrocarbon group; any two or more of the R1 to the R4 are allowed to bebonded to one another; and m and n satisfy m≧1 and n≧0.
 9. An electricvehicle comprising: a secondary battery; a conversion section convertingelectric power supplied from the secondary battery into drive power; adrive section operating according to the drive power; and a controlsection controlling a used state of the secondary battery, wherein thesecondary battery includes a cathode, an anode, and an electrolyticsolution, the anode includes an anode active material layer on an anodecurrent collector, the anode active material layer includes a carbonmaterial, the anode active material layer has a thickness from about 30micrometers to about 100 micrometers both inclusive, and theelectrolytic solution includes an unsaturated cyclic ester carbonaterepresented by the following Formula (1),

where X is a divalent group in which m-number of >C═CR1R2 and n-numberof >CR3R4 are bonded in any order; each of R1 to R4 is one of a hydrogengroup, a halogen group, a monovalent hydrocarbon group, a monovalenthalogenated hydrocarbon group, a monovalent oxygen-containinghydrocarbon group, and a monovalent halogenated oxygen-containinghydrocarbon group; any two or more of the R1 to the R4 are allowed to bebonded to one another; and m and n satisfy m≧1 and n≧0.
 10. An electricpower storage system comprising: a secondary battery; one or moreelectric devices supplied with electric power from the secondarybattery; and a control section controlling the supplying of the electricpower from the secondary battery to the one or more electric devices,wherein the secondary battery includes a cathode, an anode, and anelectrolytic solution, the anode includes an anode active material layeron an anode current collector, the anode active material layer includesa carbon material, the anode active material layer has a thickness fromabout 30 micrometers to about 100 micrometers both inclusive, and theelectrolytic solution includes an unsaturated cyclic ester carbonaterepresented by the following Formula (1),

where X is a divalent group in which m-number of >C═CR1R2 and n-numberof >CR3R4 are bonded in any order; each of R1 to R4 is one of a hydrogengroup, a halogen group, a monovalent hydrocarbon group, a monovalenthalogenated hydrocarbon group, a monovalent oxygen-containinghydrocarbon group, and a monovalent halogenated oxygen-containinghydrocarbon group; any two or more of the R1 to the R4 are allowed to bebonded to one another; and m and n satisfy m≧1 and n≧0.
 11. An electricpower tool comprising: a secondary battery; and a movable section beingsupplied with electric power from the secondary battery, wherein thesecondary battery includes a cathode, an anode, and an electrolyticsolution, the anode includes an anode active material layer on an anodecurrent collector, the anode active material layer includes a carbonmaterial, the anode active material layer has a thickness from about 30micrometers to about 100 micrometers both inclusive, and theelectrolytic solution includes an unsaturated cyclic ester carbonaterepresented by the following Formula (1),

where X is a divalent group in which m-number of >C═CR1R2 and n-numberof >CR3R4 are bonded in any order; each of R1 to R4 is one of a hydrogengroup, a halogen group, a monovalent hydrocarbon group, a monovalenthalogenated hydrocarbon group, a monovalent oxygen-containinghydrocarbon group, and a monovalent halogenated oxygen-containinghydrocarbon group; any two or more of the R1 to the R4 are allowed to bebonded to one another; and m and n satisfy m≧1 and n≧0.
 12. Anelectronic apparatus comprising a secondary battery as an electric powersupply source, wherein the secondary battery includes a cathode, ananode, and an electrolytic solution, the anode includes an anode activematerial layer on an anode current collector, the anode active materiallayer includes a carbon material, the anode active material layer has athickness from about 30 micrometers to about 100 micrometers bothinclusive, and the electrolytic solution includes an unsaturated cyclicester carbonate represented by the following Formula (1),

where X is a divalent group in which m-number of >C═CR1R2 and n-numberof >CR3R4 are bonded in any order; each of R1 to R4 is one of a hydrogengroup, a halogen group, a monovalent hydrocarbon group, a monovalenthalogenated hydrocarbon group, a monovalent oxygen-containinghydrocarbon group, and a monovalent halogenated oxygen-containinghydrocarbon group; any two or more of the R1 to the R4 are allowed to bebonded to one another; and m and n satisfy m≧1 and n≧0.